Remove bound metric instruments from the API

[jmacd]

This demonstrates how much code we can remove by eliminating bound instruments. I believe this is worthwhile and I would rather focus on optimizing the code path for extracting baggage and the performance of RecordBatch(), not individual bound instrument APIs.

Fixes #2351

[codecov]

Codecov Report

Merging #2352 (652c9cf) into main (7ce58f3) will decrease coverage by 0.1%.
The diff coverage is 100.0%.

@@           Coverage Diff           @@
##            main   #2352     +/-   ##
=======================================
- Coverage   73.6%   73.5%   -0.2%     
=======================================
  Files        175     175             
  Lines      12419   12333     -86     
=======================================
- Hits        9144    9065     -79     
+ Misses      3041    3035      -6     
+ Partials     234     233      -1     

Impacted Files	Coverage Δ
internal/metric/global/meter.go	89.3% <ø> (-0.5%)	⬇️
metric/metric_instrument.go	89.1% <ø> (-1.4%)	⬇️
metric/metrictest/meter.go	94.4% <ø> (-1.8%)	⬇️
metric/sdkapi/noop.go	88.8% <ø> (+27.3%)	⬆️
metric/sdkapi/sdkapi.go	100.0% <ø> (ø)
sdk/metric/sdk.go	80.0% <100.0%> (-0.2%)	⬇️

[MadVikingGod]

+18 -518, best kind of PRs.

I like the thrust of the code, there needs a bit of attention to lint and changelog etc.

[evantorrie]

+1 but needs a CHANGELOG entry

[jmacd]

I like the thrust of the code, there needs a bit of attention to lint and changelog etc.

Thanks. I did't want to finish this PR until I had a few people agreeing I should.

[MrAlias]

I did't want to finish this PR until I had a few people agreeing I should.

SGTM, looks like a worth while change.

[MrAlias]

golangci-lint in ./sdk/metric
benchmark_test.go:63:6: `makeManyLabels` is unused (deadcode)
func makeManyLabels(n int) [][]attribute.KeyValue {
     ^
make: *** [Makefile:139: lint] Error 1

[MadVikingGod]

I was asked to take over getting this PR to the finish line. A new PR at #2399 fixes all of the outstanding issues.