fix: make instrumentation optional

[panekj]

Fixes #6254

• I've documented the public API Changes in the appropriate CHANGELOG.md files.
• This PR was made with the help of AI.

Signed-off-by:

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.46%. Comparing base (a9ef675) to head (988c820).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6449      +/-   ##
==========================================
- Coverage   89.82%   89.46%   -0.37%     
==========================================
  Files         378      378              
  Lines      104337   107974    +3637     
  Branches   104337   107974    +3637     
==========================================
+ Hits        93724    96601    +2877     
- Misses       7015     7456     +441     
- Partials     3598     3917     +319     

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[codspeed-hq]

Merging this PR will degrade performance by 49.52%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 49 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	Restore session [memory store]	112.8 ms	223.4 ms	-49.52%

---

_{Comparing panekj:pj/gate-tracing-instrument (988c820) with main (dab87b7)}

[bnjbvr]

Thanks, looks like this is on the right track!

Let's make sure to publicize the change by indicating in the CHANGELOG.mds of each of the touched crates that instrumentation is now disabled by default, and can be re-enabled with the Cargo feature.

Also, we'd probably want to enable it on one of the CI tasks, at least, and make sure it's enabled when building the UniFFI bindings: we could either enable the instrument features for the matrix-sdk-ffi crate by default (?), or include it manually for the swift and kotlin bindings generation tasks in the xtask helper.