fix: Fix unhandled ObjectDisposedException in IconTintColorBehavior.ClearTintColor on Android

[Kay-STL]

Description of Change

Following #1883, which fixed an ObjectDisposedException crash in ApplyTintColor, this PR fixes a crash in ClearTintColor in the same manner. Other users have reported experiencing this in the replies to the original issue linked below.

Linked Issues

• Fixes [BUG] IconTintColorBehavior crash on android. #1819

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pulls

Additional information

Android only. Reproduced reliably in a production application on an Android 11 device, cannot reproduce after patch is applied.

[Kay-STL]

@dotnet-policy-service agree company="Swallowing Technologies Limited"

[brminnick]

@Kay-STL Could you update this PR to allow maintainers to edit it? I'd like to merge it but I first need to fix the merge conflict.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/allowing-changes-to-a-pull-request-branch-created-from-a-fork

[Kay-STL]

@brminnick Can't enable maintainer access since GitHub doesn't allow it on organization repos, sorry - I've fixed the conflicts, will make sure to PR from a personal repo next time :)

[christian-strydom]

Thank you so much for this fix! This solved the last of my icon tint crashes.