Allow setting of a custom connection pool host

See merge request !9445

Chat slash commands show labels correctly

Closes #28358

See merge request !9408

This allows you to set a custom host when calling
Gitlab::Database.create_connection_pool. This is necessary for load
balancing as in this case we want to inherit all settings except for the
hostname.

Add AsciiDoc snippet for CI/CD Badges

Closes #26087

See merge request !9164

This was initially not implemented simply because I forgot about the
size limit of constraint names in PostgreSQL (63 bytes). Using the old
technique we can't add foreign keys for certain tables. For example,
adding a foreign key on
protected_branch_merge_access_levels.protected_branch_id would lead to
the following key name:

    fk_protected_branch_merge_access_levels_protected_branches_protected_branch_id

This key is 78 bytes long, thus violating the PostgreSQL size
requirements.

The hashing strategy is copied from Rails' foreign_key_name() method,
which unfortunately is private and subject to change without notice.

The returned email by the GitHub API is the user's publicly visible
email address (or null if the user has not specified a public email
address in their profile)

This commit adds CI/CD Badges Snippets for AsciiDoc as requested in #26087.
I've however run into an issue in highlighting the snippet, it seems as if AsciiDoc is currently not being highlighted properly (displayed as plaintext)

Add testcase for to_asciidoc

Update test case for Badges list

Signed-off-by: Rémy Coutable <remy@rymai.me>

Adding links to user & build stage in a Build message

Closes #26500

See merge request !8641