fix(tree): prevent tooltip for non-truncated option text (#DS-4931) - #1910

Summary

Tree options showed a tooltip even when the text was not truncated. KbqTreeOption exposed only
parentTextElement, so KbqTitleDirective measured the .kbq-option-text container against the
option host — which is always bigger, so every option looked overflown.

Reported on kbq-username, but it is unchanged and correct: plain-text options were affected too.

List of notable changes:

• fixed tooltip without truncation, by exposing textElement so the clipping box is measured against itself
• added two unit tests: no tooltip when the text fits, tooltip when it is clipped

What should reviewers focus on?

Content marking its own #kbqTitleText keeps priority, so tree-select and filter-bar should be unaffected.