Enable DNS probe in DoT validation by default in R

The flags are set as follows by default:
dot_validation_latency_factor = 3
dot_validation_latency_offset_ms = 100

Due to the flag default value changed, TlsServerRevalidation test
is modified.

Bug: 188153519
Test: with the two flags unset, run resolv_integration_test twice
Test: with the two flags unset, cd packages/modules/DnsResolver && atest
Test: with the two flags set to -1, run resolv_integration_test twice
Test: with the two flags set to -1, cd packages/modules/DnsResolver && atest
Change-Id: If80569a98244817b69909319f0c1a3b7523354cf