Add DisableConfigSyncTargetPreparer to MTS

DisableConfigSyncTargetPreparer ensures that DeviceConfig sync is
disabled during the test, so the DnsResolver feature flags will
not be changed.

This fixes the flaky tests.

Bug: 254186357
Test: atest resolv_integration_test:ResolverTest#ConnectTlsServerTimeout
      on S/T devices and manually checked that the sync was disabled
Change-Id: I60a64828cad2f0ea1f3c0dd57f48ae56618abdf6