RFR: 8297292: java/nio/channels/FileChannel/FileExtensionAndMap.java is too slow [v3]

[Brian Burkhalter]

> Reduce the test’s disk space requirement by one third and the total number of files tested by half. With this change, the test was observed to still fail with a SIGBUS using JDK 11.0.15 on Linux 5.15.0-58. The test’s run time decreased by about two thirds: for one sample run from 29m56s to 10m13s in the CI on Linux-x64. A run with 50 repeats had no failures.

Brian Burkhalter has updated the pull request incrementally with one additional commit since the last revision:

  8297292: Remove FileExtensionAndMap test as the failure is covered by InternalErrorTest.java for Unsafe

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Changes:
  - all: https://git.openjdk.org/jdk/pull/12479/files
  - new: https://git.openjdk.org/jdk/pull/12479/files/0be05b22..44bc728a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12479&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12479&range=01-02

  Stats: 239 lines in 1 file changed: 0 ins; 239 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/12479.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12479/head:pull/12479

PR: https://git.openjdk.org/jdk/pull/12479