feat(otlphttp): configure response body size limit

[jstar0]

Summary

Fixes #8819.

• Add WithMaxResponseBodySize to the OTLP/HTTP trace, metric, and log exporters.
• Keep the finite 4 MiB default response-body limit and apply it after decompression.
• Treat non-positive option values as invalid and retain the default instead of disabling the safety limit.
• Use bounded reads that detect oversized responses without integer-overflow edge cases.
• Keep the generated gRPC configuration free of HTTP-only response-body settings.

Verification

• go test ./... passes in the trace, metric, and log OTLP/HTTP exporter modules.
• make precommit completed generation, formatting/lint, README validation, and module consistency checks.
• The repository-wide race run reached the pre-existing bridge/opentracing gRPC test, which failed locally with an EOF while reading the server preface; no changed package failed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.5%. Comparing base (9ba91a2) to head (4b985e9).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #8847   +/-   ##
=====================================
  Coverage   88.5%   88.5%           
=====================================
  Files        333     333           
  Lines      21101   21129   +28     
=====================================
+ Hits       18687   18718   +31     
+ Misses      2414    2411    -3     

Files with missing lines	Coverage Δ
exporters/otlp/otlplog/otlploghttp/client.go	92.3% <100.0%> (+1.3%)	⬆️
exporters/otlp/otlplog/otlploghttp/config.go	96.3% <100.0%> (+0.1%)	⬆️
...tlpmetric/otlpmetricgrpc/internal/oconf/options.go	94.3% <100.0%> (ø)
exporters/otlp/otlpmetric/otlpmetrichttp/client.go	92.7% <100.0%> (+1.4%)	⬆️
exporters/otlp/otlpmetric/otlpmetrichttp/config.go	90.0% <100.0%> (+0.5%)	⬆️
...tlpmetric/otlpmetrichttp/internal/oconf/options.go	96.8% <100.0%> (+0.1%)	⬆️
...trace/otlptracegrpc/internal/otlpconfig/options.go	94.5% <ø> (ø)
exporters/otlp/otlptrace/otlptracehttp/client.go	89.5% <100.0%> (+1.1%)	⬆️
...trace/otlptracehttp/internal/otlpconfig/options.go	93.1% <100.0%> (+0.2%)	⬆️
exporters/otlp/otlptrace/otlptracehttp/options.go	100.0% <100.0%> (ø)

... and 2 files with indirect coverage changes

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[MrAlias]

The PR adds the requested option consistently across trace, metric, and log OTLP/HTTP exporters, preserves the 4 MiB default for ordinary configurations, updates generated configuration, and adds focused tests.

[jstar0]

Heads-up while refreshing this branch: current main now ships its own response-body limit (package-level maxResponseBodySize var, enforced via http.MaxBytesReader with MaxBytesError handling, from the changes around #8876). That limit is not user-configurable — the variable exists so tests can override it — while this PR adds WithMaxResponseBodySize as a per-exporter option.

The two overlap, so before I rebase I'd like to align on the intended shape:

1. Compose them (my preference): keep main's package var as the default source, and let WithMaxResponseBodySize override it per exporter. This preserves TestResponseBodySizeLimit's var-override pattern unchanged and adds the configurability this PR (and feat(otlphttp): configure response body size limit #8819) ask for.
2. Var-only: if maintainers prefer the non-configurable cap as final, this PR becomes redundant for the option parts and I can close it in favor of main's implementation.

Happy to rebase under either decision — the option plumbing (oconf + trace/metric/log exporters) is already in place on this branch.

[jstar0]

Merged current main and composed the two limits as described above:

• Package-level maxResponseBodySize remains the default (tests can still override it).
• WithMaxResponseBodySize overrides that default per exporter.
• Every response-body read, including WithMaxResponseBodySize(math.MaxInt64), goes through http.MaxBytesReader.
• Changelog entry now names the three HTTP exporter modules.

Verified with go test in otlptracehttp, otlpmetrichttp, otlploghttp, plus their otlpconfig/oconf packages.