[Test] Fix DNS resolver MTS failures

In MTS, test infra installs only the DNS resolver module without
installing tethering module. The test utils should not assume the BPF
maps defined in tethering will be in the device.

Bug: 309164580
Test: atest
resolv_integration_test:ResolverTest#BlockDnsQueryWithUidRule

Change-Id: I2c7349a11c9b413c129c93d236c8280588097cf7