RFR: 8286475: Drop --enable-preview from instanceof pattern matching related tests [v2]

[Aleksey Shipilev]

> There are plenty of tests failing on many architectures due to `--enable-preview` VM code introduced by Loom. This improvement eliminates some of the redundant `--enable-preview` clauses from the instanceof pattern matching tests, since instanceof pattern matching have been graduated from preview in JDK 16. 
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug, affected tests still pass
>  - [x] Linux x86_32 fastdebug, affected tests start to pass

Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:

  Copyright years

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8628/files
  - new: https://git.openjdk.java.net/jdk/pull/8628/files/c2da78bf..8dcdff4d

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8628&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8628&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8628.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8628/head:pull/8628

PR: https://git.openjdk.java.net/jdk/pull/8628