Fix issue with linking email to anonymous accounts on desktop

[a-maurice]

Description

Provide details of the change, and generalize the change in the PR title above.

Changes to email enumeration protection broke some functionality on the backend with email accounts. One of those is upgrading anonymous accounts to have email and password. This can be fixed by using a slightly different rest call, so this makes that change for desktop, mobile platforms will be fixed in the underlying mobile SDKs.

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Testing

Describe how you've tested these changes. Link any manually triggered Integration tests or CPP binary SDK Packaging Github Action workflows, if applicable.

Testing locally with a custom project that has email enumeration protection turned on.

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Type of Change

Place an x the applicable box:

• Bug fix. Add the issue # below if applicable.
• New feature. A non-breaking change which adds functionality.
• Other, such as a build process or documentation change.

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Notes

• Bug fixes and feature changes require an update to the Release Notes section of release_build_files/readme.md.
• Read the contribution guidelines CONTRIBUTING.md.
• Changes to the public API require an internal API review. If you'd like to help us make Firebase APIs better, please propose your change in a feature request so that we can discuss it together.

[github-actions]

Integration test with FLAKINESS (succeeded after retry)

Requested by @a-maurice on commit 08f43f1
Last updated: Tue Dec 19 18:35 PST 2023
View integration test log & download artifacts

Failures	Configs
firestore	[TEST] [FLAKINESS] [Android] [1/3 os: macos] [1/2 android_device: android_target] (1 failed tests)   CRASH/TIMEOUT [TEST] [FLAKINESS] [Android] [1/3 os: ubuntu] [1/2 android_device: emulator_ftl_target] (1 failed tests)   ServerTimestampTest.TestServerTimestampsWorkViaTransactionSet
remote_config	[TEST] [FLAKINESS] [Android] [1/3 os: ubuntu] [1/2 android_device: emulator_ftl_target] (1 failed tests)   FirebaseRemoteConfigTest.TestAddOnConfigUpdateListener

Add flaky tests to go/fpl-cpp-flake-tracker

[a-maurice]

Removing tests failed tag, since it is just caused by backend problems that aren't part of this change