CDRIVER-4106 Update numbers for existing SRV polling prose tests. (#845)

Only prose test 9 is currently implemented according to spec. Behavior of
test_srv_polling_mocked does not conform to prose tests described by spec.
Therefore, only names related to prose test 9 are updated with numbering.

Prose tests 1 through 8 are to be implemented separately; see
CDRIVER-4125.