Tapping Enter in citations to split block also adds a new line

[mchowning]

Describe the bug
On Android only, when tapping enter at the end of a quote or pullquote block citation to split the block, the block is split, but a new empty line is also added to the citation. No new line should be added.

To Reproduce
Steps to reproduce the behavior:

1. Add a Quote block
2. Add some text to the citation
3. Tap Enter
4. Observe that a new paragraph block has been created
5. Observe that the quote block's citation now has a second line (i.e., there is a <br> in the html).

Expected behavior
Tapping Enter within a citation should split the block without adding a new line to the citation.

Screenshots

Smartphone (please complete the following information):

• Device: Pixel 1
• OS: Android X
• Version 15.2.1

[guarani]

A quick test on WPAndroid 15.2.1 indicates that this happens when using the Gboard keyboard but not when using the Samsung keyboard.

[AmandaRiu]

FYI: This is still an issue as of 1.57.0 (figured I'd make a note of it since I was already doing the writing flow testing for this release).

[SiobhyB]

Making a note that this is still an issue as of 19.2-rc-1, testing on a Pixel 5 (Android 12).

[SiobhyB]

Noting that this is still an issue as of 22.0-rc-1, testing on a Pixel 6 (Android 13).