RFR: 8286441: Remove mode parameter from jdk.internal.perf.Perf.attach() [v2]

[Ioi Lam]

> The `mode` parameter for ` jdk.internal.perf.Perf.attach()` has never supported the value `"rw"` since the source code was imported to the openjdk repo more than 15 years ago. In fact HotSpot throws `IllegalArgumentException` when such a mode is specified.
> 
> It's unlikely such a mode will be required for future enhancements. Support for `"rw"` is removed. The "mode" parameter is also removed, since now `"r"` is the only supported mode.
> 
> I also cleaned up related code in the JDK and HotSpot.
> 
> Testing:
> - Passed tiers 1 and 2
> - Tiers 3, 4, 5 are in progress

Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:

  review comments

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8622/files
  - new: https://git.openjdk.java.net/jdk/pull/8622/files/22c22c30..34a01f71

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8622&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8622&range=00-01

  Stats: 14 lines in 5 files changed: 1 ins; 7 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8622.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8622/head:pull/8622

PR: https://git.openjdk.java.net/jdk/pull/8622