‐Fix for #5547

Closes #5547

What has been done to verify that this works as intended?

Tested manually.

Why is this the best possible solution? Were any other approaches considered?

Aligns behaviour of phonePreference in FormMetadataPreferencesFragment with StringWidget.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

Behaviour is now as desired. Doesn't break any tests.

Do we need any specific form for testing your changes? If so, please attach one.

No (and not possible)?

Does this change require updates to documentation? If so, please file an issue here and include the link below.

No.

Before submitting this PR, please make sure you have:

• run ./gradlew checkAll and confirmed all checks still pass OR confirm CircleCI build passes and run ./gradlew connectedDebugAndroidTest locally.
• verified that any code or assets from external sources are properly credited in comments and/or in the about file.
• verified that any new UI elements use theme colors. UI Components Style guidelines

SavePointTest whenEditing_savePointIsCreatedWhenLeavingTheApp IdentifyUserTest openingForm_andRotating_remainsOnIdentityPrompt PreviouslyDownloadedOnlyTest whenPreviouslyDownloadedOnlyEnabledWithAutomaticDownload_checkingAutoDownload_downloadsUpdatedForms_andDisplaysNotification FormMapTest fillingBlankForm_addsInstanceToMap AboutPageTest when_OpenSourcesLibrariesLicenses_should_openSourceLicensesTitleBeDisplayed