Default transcript dumping in "statistics dump" to false (#145436)

### Summary
Currently, if the setting `interpreter.save-transcript` is enabled,
whenever we call "statistics dump", it'll default to reporting a huge
list of transcripts which can be a bit noisy. This is because the
current check `GetIncludeTranscript` returns `!GetSummaryOnly()` by
default if no specific transcript-setting option is given in the
statistics dump command (ie. `statistics dump --transcripts=false` or
`statistics dump --transcripts=true`). Then when
`interpreter.save-transcript` is enabled, this saves a list of
transcripts, and the transcript list ends up getting logged by default.

These changes default the option to log transcripts in the `statistics
dump` command to "false". This can still be enabled via the
`--transcripts` option if users want to see a transcript. Since
`interpreter.save-transcript` is false by default, the main delta is
that if `interpreter.save-transcript` is true and summary mode is false,
we now disable saving the transcript.

This also adds a warning to 'statistics dump --transcript=true' when
interpreter.save-transcript is disabled, which should help users
understand
why transcript data is empty.

### Testing

#### Manual testing
Tested with `settings set interpreter.save-transcript true` enabled at
startup on a toy hello-world program:
```
(lldb) settings set interpreter.save-transcript true
(lldb) target create "/home/qxy11/hello-world/a.out"
Current executable set to '/home/qxy11/hello-world/a.out' (x86_64).
(lldb) statistics dump
{
  /* no transcript */
}
(lldb) statistics dump --transcript=true
{
"transcript": [
    {
      "command": "statistics dump",
      "commandArguments": "",
      "commandName": "statistics dump",
      "durationInSeconds": 0.0019650000000000002,
      "error": "",
      "output": "{...
    },
    {
      "command": "statistics dump --transcript=true",
      "commandArguments": "--transcript=true",
      "commandName": "statistics dump",
      "timestampInEpochSeconds": 1750720021
    }
  ]
}
```
Without `settings set interpreter.save-transcript true`:
```
(lldb) target create "/home/qxy11/hello-world/a.out"
Current executable set to '/home/qxy11/hello-world/a.out' (x86_64).
(lldb) statistics dump
{
  /* no transcript */
}
(lldb) statistics dump --transcript=true
{
  /* no transcript */
}
warning: transcript requested but none was saved. Enable with 'settings set interpreter.save-transcript true'
```

#### Unit tests
Changed unit tests to account for new expected default behavior to
`false`, and added a couple new tests around expected behavior with
`--transcript=true`.
```
lldb-dotest -p TestStats ~/llvm-sand/external/llvm-project/lldb/test/API/commands/statistics/basic/
```

lldb/source/Commands/CommandObjectStats.cpp

@@ -9,6 +9,7 @@
 #include "CommandObjectStats.h"
 #include "lldb/Core/Debugger.h"
 #include "lldb/Host/OptionParser.h"
+#include "lldb/Interpreter/CommandInterpreter.h"
 #include "lldb/Interpreter/CommandOptionArgumentTable.h"
 #include "lldb/Interpreter/CommandReturnObject.h"
 #include "lldb/Interpreter/OptionArgParser.h"
@@ -147,9 +148,18 @@ protected:
     if (!m_options.m_all_targets)
       target = m_exe_ctx.GetTargetPtr();
 
+    // Check if transcript is requested but transcript saving is disabled
+    const StatisticsOptions &stats_options = m_options.GetStatisticsOptions();
+    if (stats_options.GetIncludeTranscript() &&
+        !GetDebugger().GetCommandInterpreter().GetSaveTranscript()) {
+      result.AppendWarning(
+          "transcript requested but none was saved. Enable with "
+          "'settings set interpreter.save-transcript true'");
+    }
+
     result.AppendMessageWithFormatv(
-        "{0:2}", DebuggerStats::ReportStatistics(
-                     GetDebugger(), target, m_options.GetStatisticsOptions()));
+        "{0:2}",
+        DebuggerStats::ReportStatistics(GetDebugger(), target, stats_options));
     result.SetStatus(eReturnStatusSuccessFinishResult);
   }
 

lldb/source/Commands/Options.td

@@ -1482,13 +1482,15 @@ let Command = "statistics dump" in {
     "this is turned off unless specified. "
     "In default mode, if both '--targets' and '--modules' are 'true', a list "
     "of module identifiers will be added to the 'targets' section.">;
-  def statistics_dump_transcript: Option<"transcript", "t">, Group<1>,
-    Arg<"Boolean">,
-    Desc<"If the setting interpreter.save-transcript is enabled and this "
-    "option is 'true', include a JSON array with all commands the user and/or "
-    "scripts executed during a debug session. "
-    "Defaults to true, unless the '--summary' mode is enabled, in which case "
-    "this is turned off unless specified.">;
+  def statistics_dump_transcript
+      : Option<"transcript", "t">,
+        Group<1>,
+        Arg<"Boolean">,
+        Desc<"If the setting interpreter.save-transcript is enabled and this "
+             "option is 'true', include a JSON array with all commands the "
+             "user and/or "
+             "scripts executed during a debug session. "
+             "Defaults to false. ">;
   def statistics_dump_plugins
       : Option<"plugins", "p">,
         Group<1>,