[jdk11u-dev] RFR: 8254850: Update terminology in java.awt.GridBagLayout source code comments

[Aleksey Shipilev]

Clean backport to match `11.0.13-oracle`.

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Commit messages:
 - Backport 9ed0b7640338194365f7d8a53bc2df3b0c96e821

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/240/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=240&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254850
  Stats: 10 lines in 1 file changed: 0 ins; 0 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/240.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/240/head:pull/240

PR: https://git.openjdk.java.net/jdk11u-dev/pull/240