fix: clean up agenda personalization links

[jennifer-richards]

Fixes #3786 and #3787

[codecov]

Codecov Report

Merging #3803 (027d1dc) into feat/bs5 (8bd4851) will increase coverage by 0.00%.
The diff coverage is 98.21%.

❗ Current head 027d1dc differs from pull request most recent head 68bf84a. Consider uploading reports for the commit 68bf84a to get more accurate results

@@            Coverage Diff            @@
##           feat/bs5    #3803   +/-   ##
=========================================
  Coverage     87.97%   87.98%           
=========================================
  Files           296      297    +1     
  Lines         38795    38804    +9     
=========================================
+ Hits          34130    34140   +10     
+ Misses         4665     4664    -1     

Impacted Files	Coverage Δ
ietf/meeting/models.py	86.08% <ø> (ø)
ietf/meeting/utils.py	90.27% <ø> (-0.29%)	⬇️
ietf/meeting/views.py	90.73% <95.00%> (+0.02%)	⬆️
ietf/doc/templatetags/ballot_icon.py	84.89% <100.00%> (ø)
ietf/doc/templatetags/ietf_filters.py	81.25% <100.00%> (ø)
ietf/doc/views_ballot.py	91.60% <100.00%> (ø)
ietf/doc/views_charter.py	88.72% <100.00%> (ø)
ietf/doc/views_status_change.py	93.04% <100.00%> (ø)
ietf/ietfauth/views.py	90.57% <100.00%> (ø)
ietf/liaisons/widgets.py	86.11% <100.00%> (ø)
... and 7 more

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[rjsparks]

No - this isn't right - The buttons are supposed to be on the main agenda page as well as the other page, as they are pre-bs5.
After someone customizes with either mechanic, they should be able to easily subscribe or download ics.

[jennifer-richards]

Yeah, I lost track of which buttons these were. It's just the link back to the customized agenda view that needed to be limited. They all needed to be made visible on the personalize tab. Thanks for catching it.

[jennifer-richards]

This update restores the webcal / .ics buttons to the agenda tab. It relabels them as "filtered agenda" instead of "personal agenda." It also suppresses the duplicate set of buttons at the very end of the agenda tab. On the personalize tab, these are meant to be useful to someone who has gone through the whole page to select individual sessions, but there's little need for them on the agenda tab.