RFR: 8303444: AsyncGetCallTrace obtains too few frames with instrumentation agent

[Johannes Bechberger]

This fixes the bug by removing the faulty completeness check for runtime blobs.

I tested it using the [trace_validation](https://github.com/parttimenerd/trace_validation) tool successfully as described in the issue. I furthermore ran the [jdk-profiling-tester](https://github.com/parttimenerd/jdk-profiling-tester) to ensure that this fix did not introduce any stability issues and ran the serviceability JTREG tests successfully.

-------------

Commit messages:
 - Don't check for completeness of runtime stubs

Changes: https://git.openjdk.org/jdk/pull/12804/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12804&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303444
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12804.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12804/head:pull/12804

PR: https://git.openjdk.org/jdk/pull/12804