Term Meta: Multiple primary key defined

[ocean90]

While working on #34209 I noticed the following error while upgrading the database:

WordPress database error: [Multiple primary key defined]
ALTER TABLE wp_termmeta ADD PRIMARY KEY (meta_id)

[ocean90]

In 34936:

Term Meta: Prevent a "Multiple primary key defined" error during database upgrades.

You must have two spaces between the words PRIMARY KEY and the definition of your primary key. Yes, seriously.

See [34529].
Fixes #34210.