RFR: 8320365: IPPrintService.getAttributes() causes blanket re-initialisation

[Phil Race]

Whilst reviewing the fix for https://bugs.openjdk.org/browse/JDK-7001133 I realised that although the proposed
changes there may help, the problem would be inconsequential except that if anything causes an app to
call PrintService.getAttributes()  we will continually be re-initialising attributes, which causes IPPPrintService
to keep creating new instances of CUPSPrinter which are then discarded and over-written.
So update the implementation to only re-initialise the relevant attributes.

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Commit messages:
 - 8320365

Changes: https://git.openjdk.org/jdk/pull/16752/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16752&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320365
  Stats: 19 lines in 1 file changed: 10 ins; 0 del; 9 mod
  Patch: https://git.openjdk.org/jdk/pull/16752.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16752/head:pull/16752

PR: https://git.openjdk.org/jdk/pull/16752