[dv] The TCK frequence in jtag_if is not configured explicitly for top-level tests

[rswarbrick]

Description

At the moment, the frequency comes from jtag_if.sv itself. Making this frequency more sensible for GLS meant we needed to add an ifdef (issue #24580). To make this a bit clearer, we should probably:

1. Add something to the top-level test UVM configuration to explicitly set a JTAG frequency.
2. Make the frequency silly if it hasn't been configured, but overridden by something sensible for GLS.
3. "For extra credit": Come up with some way to configure this sensibly for GLS to avoid needing to encode facts about the technology target for Earlgrey into jtag_if.sv(!)