Improve silence benchmarks (#4722)

* Add GC benchmarks

Signed-off-by: Guido Trotter <[email protected]>

* benchmarkQuery: set silences via Set()

Signed-off-by: Guido Trotter <[email protected]>

* Add BenchmarkMutesIncremental test

This helps us check how Mutes behaves when there are many silences, and
a few more trickle in between Mutes calls.

Signed-off-by: Guido Trotter <[email protected]>

* Adjust BenchmarkMutes to be more realistic

Signed-off-by: Guido Trotter <[email protected]>

* Reduce noise in bench tests by adding WithLogger(quartz.NoOpLogger)

Signed-off-by: Guido Trotter <[email protected]>

* Simplify BenchmarkMutesParallel and BenchmarkQueryParallel

The numGoRoutines parameter was unused, so the maximum was always used.
Simplify the tests to stick to this.

Signed-off-by: Guido Trotter <[email protected]>

* TestSilenceGCOverTime: check different groups of expiring silences expire correctly over time

Signed-off-by: Guido Trotter <[email protected]>

* BenchmarkGC: simplify and make runtime manageable

Signed-off-by: Guido Trotter <[email protected]>

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Signed-off-by: Guido Trotter <[email protected]>
Co-authored-by: Guido Trotter <[email protected]>

Author: ultrotter