[jdk21u-dev] RFR: 8328005: Convert java/awt/im/JTextFieldTest.java applet test to main

[Goetz Lindenmaier]

I backport this for parity with 21.0.7-oracle

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Commit messages:
 - Backport cc5cda558736ffeae2a4611d87dfe280b9a4eac3

Changes: https://git.openjdk.org/jdk21u-dev/pull/1258/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1258&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8328005
  Stats: 68 lines in 2 files changed: 11 ins; 32 del; 25 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1258.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1258/head:pull/1258

PR: https://git.openjdk.org/jdk21u-dev/pull/1258