Revert "Merge branch '118442-restyle-changes-header-and-file-tree' into 'master'"

What does this MR do?

This MR reverts !22364 (merged) which introduced a number of regressions in the Web IDE:

• #197493 (closed)
• #198002 (closed)
• #198029 (closed)
• #198057 (closed)

Screenshots

Description	Screenshot on f0bb99d0
Nested dropdown not showing is fixed.
Duplicate changed icons showing is fixed.
Changed icon in tab alignment is fixed.
Delete status icon persisting after discard is fixed.
MR UX enhancements are reverted.