[ZEPPELIN-6517] Add E2E tests for notebook paragraph components

[miinhho]

What is this PR for?

This PR improves the behavior-focused E2E coverage for the notebook paragraph sub-components.

It replaces shallow visibility checks and interpreter-error fallbacks with scenarios that verify user-observable paragraph behavior:

• Add paragraphs above and below the current paragraph
• Edit Monaco content and verify focused, dirty, and rendered line states
• Inspect the paragraph settings available for single and multiple paragraphs
• Clone, insert, move, and remove paragraphs
• Toggle the editor, output, line numbers, and run state
• Edit paragraph titles and verify Enter, Escape, and blur behavior
• Verify running, finished, outdated, and cancelled paragraph states
• Verify progress and footer timing information
• Verify that paragraph insertion is disabled while execution is in progress

The paragraph page object is also updated to:

• Scope component locators to the primary paragraph
• Provide helpers for add-paragraph and settings-menu interactions
• Replace individual settings-menu locators with a typed settingsMenuItem() accessor
• Support interactions with settings menus belonging to different paragraphs
• Use stable, component-specific locators instead of broad fallback selectors

What type of PR is it?

Improvement

What is the Jira issue?

• https://issues.apache.org/jira/browse/ZEPPELIN-6517

How should this be tested?

From zeppelin-web-angular/, run:

npm run e2e:fast -- tests/notebook/paragraph/paragraph-functionality.spec.ts

Questions:

• Does the license files need to update? No
• Is there breaking changes for older versions? No
• Does this needs documentation? No

[tbonelee]

Could you rebase this onto master?

[voidmatcha]

.

[voidmatcha]

Nice rework, replacing shallow visibility checks with behavior-focused scenarios. A couple of things:

Must fix: The @NB-PARITY-003/004 tags got dropped, so this PR's frontend CI is failing (log). Candidate fix: https://github.com/voidmatcha/zeppelin/tree/review/pr5476-parity-check

Unrelated bug found (ZEPPELIN-6710): While verifying this test I ran into a pre-existing bug unrelated to this PR — under CI load, Monaco's word-based suggestion swallows Enter and drops a line (line threeline four). Filed a separate ticket and put up a candidate fix: https://github.com/voidmatcha/zeppelin/tree/fix/monaco-word-suggest-enter-race (11/11 on webkit+firefox). Once that lands, the flakiness here should go away too.

Minor (non-blocking): getElapsedTime() returns 'Running…' before dateStarted is set, but the two new tests only expect /^Started .+ ago\.$/, so this could be occasionally flaky on slow CI. Fix included in the review/pr5476-parity-check branch above.