A couple of small integrations fixes

[Lukewh]

Done

• Fixed badly worded error
• Fixed incorrect rendering of channel

How to QA

• Visit https://charmhub-io-1603.demos.haus/mysql/integrations
  • The final section should read "No charms found that provide s3"
  • For the the "db-router" relation "Mysql Router" should have the channel "8.0/stable" not "8.0/stable/8.0"

Issue / Card

Fixes #1598
Fixes https://warthogs.atlassian.net/browse/WD-4449

Screenshots

[webteam-app]

Demo starting at https://charmhub-io-1603.demos.haus

[codecov]

Codecov Report

Merging #1603 (d3a04ae) into main (f682882) will decrease coverage by 0.47%.
The diff coverage is 4.00%.

❗ Current head d3a04ae differs from pull request most recent head aa6dd95. Consider uploading reports for the commit aa6dd95 to get more accurate results

@@            Coverage Diff             @@
##             main    #1603      +/-   ##
==========================================
- Coverage   34.52%   34.06%   -0.47%     
==========================================
  Files          16       16              
  Lines        1393     1415      +22     
==========================================
+ Hits          481      482       +1     
- Misses        912      933      +21     

Flag	Coverage Δ
python	34.06% <4.00%> (-0.47%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
webapp/interfaces/views.py	28.16% <ø> (ø)
webapp/interfaces/logic.py	17.09% <4.00%> (-1.62%)	⬇️

[chillkang]

LGTM 👍