Fix bound instruments pinning context-derived attributes

[jaydeluca]

ExtendedLongCounter.bind(Attributes) and its sibling APIs currently resolve their target time series at bind time. As part of that lookup, each applicable view's AttributesProcessor runs against Context.current(). If a view derives attributes from context (the only currently supported examples are SdkMeterProviderUtil.appendAllBaggageAttributes and appendFilteredBaggageAttributes) then subsequent measurements through the bound instrument remain pinned to the baggage that was current at bind time, rather than using the context supplied at record time.

Depending on the usage pattern, this either drops the context-derived attributes entirely when binding at startup, misattributes later requests to an earlier request's baggage when a binding is reused, or eagerly creates one series per distinct bind-time baggage set when binding per request, eventually exhausting the cardinality limit.

AttributesProcessor.usesContext() prevents this eager binding and is still documented as doing so. Before bound instruments were removed, DefaultSynchronousMetricStorage.bind() returned a late-bound handle when usesContext() was true.

That guard and fallback handle were deleted from DefaultSynchronousMetricStorage in #5157.

When bound instruments returned in #8527, the new cumulative and delta bind paths processed attributes against Context.current() without restoring that check.

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.30%. Comparing base (35636ae) to head (d6c7974).
⚠️ Report is 22 commits behind head on main.

Files with missing lines	Patch %	Lines
...nternal/state/DefaultSynchronousMetricStorage.java	75.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8782      +/-   ##
============================================
+ Coverage     91.27%   91.30%   +0.02%     
- Complexity    10472    10509      +37     
============================================
  Files          1006     1007       +1     
  Lines         28277    28387     +110     
  Branches       3569     3588      +19     
============================================
+ Hits          25811    25918     +107     
  Misses         1674     1674              
- Partials        792      795       +3     

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[jack-berg]

Yeah this is why I want to go forward with #8719 - the machinery needed to maintain this unspecified feature is growing in size / complexity.

I think this PR is correct, but before we proceed, let's talk about #8719 at the next java SIG to see where that falls. If folks agree, then I believe we can skip this.