RFR: 8311031: JTable header border vertical lines are not aligned with data grid lines

[Tejesh R]

The header border uses `g.drawLine` whereas the JTable data grid lines uses `SwingUtilities2.drawVLine` and `SwingUtilities2.drawHLine` to draw horizontal and vertical lines. The SwingUtilities2 uses `Graphics.fillRect` which contributes to the difference between the position of these two lines which happens/visible at higher ui scaling (difference in alignment between vertical lines of these two). The fix propose to use the same methods for metal L&F of JTable header border paint. 
CI testing shows green.

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Commit messages:
 - Remove white space from test
 - Fix + Manual Test

Changes: https://git.openjdk.org/jdk/pull/14766/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14766&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311031
  Stats: 93 lines in 2 files changed: 89 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/14766.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14766/head:pull/14766

PR: https://git.openjdk.org/jdk/pull/14766