feat: allow setting a timeout for mysql try lock

[vgarvardt]

Timeout for GET_LOCK() for mysql driver is currently hardcoded to 10 seconds. This PR allows setting a custom value for the timeout.

[vgarvardt]

Tests are failing with

=== NAME  TestMigrate/cockroachdb/cockroach:v1.1.9
    dktest.go:185: Failed: error pulling image: cockroachdb/cockroach:v1.1.9 error: Error response from daemon: manifest for cockroachdb/cockroach:v1.1.9 not found: manifest unknown: manifest unknown
=== NAME  TestMigrate/cockroachdb/cockroach:v2.0.7
    dktest.go:185: Failed: error pulling image: cockroachdb/cockroach:v2.0.7 error: Error response from daemon: manifest for cockroachdb/cockroach:v2.0.7 not found: manifest unknown: manifest unknown
=== NAME  TestMigrate/cockroachdb/cockroach:v1.0.7
    dktest.go:185: Failed: error pulling image: cockroachdb/cockroach:v1.0.7 error: Error response from daemon: manifest for cockroachdb/cockroach:v1.0.7 not found: manifest unknown: manifest unknown
=== NAME  TestMigrate/cockroachdb/cockroach:v2.1.3
    dktest.go:185: Failed: error pulling image: cockroachdb/cockroach:v2.1.3 error: Error response from daemon: manifest for cockroachdb/cockroach:v2.1.3 not found: manifest unknown: manifest unknown
--- FAIL: TestMigrate (0.00s)
    --- FAIL: TestMigrate/cockroachdb/cockroach:v1.1.9 (0.12s)
    --- FAIL: TestMigrate/cockroachdb/cockroach:v2.0.7 (0.13s)
    --- FAIL: TestMigrate/cockroachdb/cockroach:v1.0.7 (0.13s)
    --- FAIL: TestMigrate/cockroachdb/cockroach:v2.1.3 (0.14s)

that has nothing to do with the PR