refactor: migrate from PortalToFollowElem to Popover component across various components

[CodingOnStar]

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Summary

This commit updates multiple components to replace the PortalToFollowElem with the new Popover component, enhancing the UI consistency and functionality. The changes include adjustments in the trigger and content handling for the Popover, ensuring proper event management and styling. Additionally, tests have been updated to reflect these changes.

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint && make type-check (backend) and cd web && pnpm exec vp staged (frontend) to appease the lint gods

[codecov]

Codecov Report

❌ Patch coverage is 87.58170% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.54%. Comparing base (3b24d8d) to head (057de05).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
...s/_base/components/variable/var-reference-vars.tsx	77.27%	5 Missing ⚠️
...mponents/variable/var-reference-picker.trigger.tsx	86.36%	3 Missing ⚠️
...nodes/_base/components/agent-strategy-selector.tsx	85.71%	2 Missing ⚠️
...ents/delivery-method/recipient/member-selector.tsx	50.00%	2 Missing ⚠️
...ge-retrieval/components/metadata/add-condition.tsx	0.00%	2 Missing ⚠️
...components/workflow/block-selector/tool-picker.tsx	93.75%	1 Missing ⚠️
..._base/components/variable/var-reference-picker.tsx	92.30%	1 Missing ⚠️
...orkflow/nodes/if-else/components/condition-add.tsx	66.66%	1 Missing ⚠️
...dition-list/condition-common-variable-selector.tsx	85.71%	1 Missing ⚠️
...s/workflow/nodes/loop/components/condition-add.tsx	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #35454      +/-   ##
==========================================
+ Coverage   85.51%   85.54%   +0.02%     
==========================================
  Files        4437     4438       +1     
  Lines      207128   207214      +86     
  Branches    38589    38623      +34     
==========================================
+ Hits       177120   177253     +133     
+ Misses      26897    26850      -47     
  Partials     3111     3111              

Flag	Coverage Δ
dify-ui	93.01% <ø> (ø)
web	86.43% <87.58%> (+0.06%)	⬆️

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