fix an issue IsMFARequired returns false when database name does not match

[greedy52]

changelog: fix an issue Postgres database cannot be accessed via Teleport Connect when per-session MFA is enabled and the role does not have wildcard db_names

note that the fix is on Auth service

Before

Connect (good access):
no mfa prompt then

tsh (bad access):

# no MFA tap but shows access to db denied error
$ tsh db connect --db-user teleport-admin my-postgres-sales --db-name not-allowed
psql: error: connection to server at "localhost" (::1), port 60876 failed: Connection refused
	Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (127.0.0.1), port 60876 failed: access to db denied. User does not have permissions. Confirm database user and name.
ERROR: exit status 2

After

Connect (good access):

tsh (bad access):

# now must present MFA tap before observing the access denied error
$ tsh db connect --db-user teleport-admin my-postgres-sales --db-name not-allowed
MFA is required to access Database "my-postgres-sales"
Tap any security key
Detected security key tap
psql: error: connection to server at "localhost" (::1), port 62545 failed: Connection refused
	Is the server running on that host and accepting TCP/IP connections?
connection to server at "localhost" (127.0.0.1), port 62545 failed: access to db denied. User does not have permissions. Confirm database user and name.

[backport-bot-workflows]

@greedy52 See the table below for backport results.

Branch	Result
branch/v17	Create PR
branch/v18	Create PR