Fix #20664 - fix crash in WPAvatarUtils

[maxme]

Fixes #20664

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Regression Notes

1. Potential unintended areas of impact

   • This will have the same behavior as before the Gravatar-SDK-Android integration: if the passed Gravatar URL is invalid (no or empty hash), we'll show the default avatar.

2. What I did to test those areas of impact (or what existing automated tests I relied on)

   • I haven't tested manually

3. What automated tests I added (or what prevented me from doing so)

   • New test added in WPAvatarUtilsTests

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PR Submission Checklist:

• [x] I have completed the Regression Notes.
• [x] I have considered adding accessibility improvements for my changes.
• [x] I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

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Testing Checklist (strike-out the not-applying and unnecessary ones):

~- [ ] WordPress.com sites and self-hosted Jetpack sites.~ ~- [ ] Portrait and landscape orientations.~ ~- [ ] Light and dark modes.~ ~- [ ] Fonts: Larger, smaller and bold text.~ ~- [ ] High contrast.~ ~- [ ] Talkback.~ ~- [ ] Languages with large words or with letters/accents not frequently used in English.~ ~- [ ] Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)~ ~- [ ] Large and small screen sizes. (Tablet and smaller phones)~ ~- [ ] Multi-tasking: Split screen and Pop-up view. (Android 10 or higher)~

[dangermattic]

	1 Warning
:warning:	This PR is assigned to the milestone 24.7 ❄️. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

Generated by :no_entry_sign: Danger

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20668-a97c114
	Commit	a97c114118c7d2ad0d68954db95856d0de264de8
	Direct Download	jetpack-prototype-build-pr20668-a97c114.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20668-a97c114
	Commit	a97c114118c7d2ad0d68954db95856d0de264de8
	Direct Download	wordpress-prototype-build-pr20668-a97c114.apk

Note: Google Login is not supported on these builds.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 40.46%. Comparing base (687b082) to head (a97c114). Report is 2 commits behind head on release/24.7.

Files	Patch %	Lines
...java/org/wordpress/android/util/WPAvatarUtils.java	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release/24.7 #20668 +/- ## ============================================= Coverage 40.46% 40.46% ============================================= Files 1484 1484 Lines 68416 68416 Branches 11307 11307 ============================================= Hits 27683 27683 Misses 38233 38233 Partials 2500 2500 ```

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