RFR: CODETOOLS-7903304: Remove support for obsolete SCM systems

Wed Sep 14 00:37:28 UTC 2022

Please review a fairly simple update to remove support for very (very) old SCM systems, such as SCCS, TeamWare, RCS, CVS.

Mostly this consists of reducing the set of filenames to be ignored when scanning the file system.  
The check for the SCCS artifact `@(#)` as "not a tag" is also removed.

One test is removed, which checked that files beginning with `,` were ignored. This was an SCCS artifact.

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Commit messages:
 - CODETOOLS-7903304: Remove support for obsolete SCM systems

Changes: https://git.openjdk.org/jtreg/pull/120/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=120&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903304
  Stats: 102 lines in 6 files changed: 0 ins; 99 del; 3 mod
  Patch: https://git.openjdk.org/jtreg/pull/120.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/120/head:pull/120

PR: https://git.openjdk.org/jtreg/pull/120