fix(api): preserve tracestate member order when truncating over 32 items

[zigzagdev]

Which problem is this PR solving?

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context. List any dependencies that are required for this change.

TraceStateImpl (in @opentelemetry/api, api/src/trace/internal/tracestate-impl.ts) truncates tracestate entries when there are more than 32 members.
The truncation logic reversed the entry list to slice off the oldest members, but never reversed the result back before rebuilding the internal Map, breaking the map's reverse-insertion-order convention.
As a result, serialize() on a truncated TraceStateImpl emitted members in reverse order, violating the W3C tracestate ordering requirement (most recently updated member first).

Fixes # (issue)

Short description of the changes

• Added a .reverse() call after slice() in _parse() so the internal map's insertion order is restored after truncation.
• Extended the existing truncation test to assert serialize() preserves the original member order after truncating over-limit entries.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Ran api/test/common/trace/tracestate.test.ts (transpile-only mocha run) — all 12 tests pass, including the new order assertion.

• Manually reproduced the truncation logic in a standalone Node script with a 5-member tracestate truncated to 3 members, confirming the serialized order matches the expected "e=5,d=4,c=3" (previously produced "c=3,d=4,e=5").

• Test A: npx mocha 'test/common/trace/tracestate.test.ts in api/

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added
• Documentation has been updated

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