Bugfixing RTCM for v5.2

[ArturSztuc]

Bugfixing RandomTCMaker after v5.2 performance tests.

Bug: when running with trigger rate of 0.01Hz or lower, RTCM would spit out TCs at much higher rate.
Fix: The issue was with using int for time intervals rather than uint64_ts. Changed from int to uint64_t
Test: Ran test configuration with low trigger rate (0.01Hz) on code before and after the fix for 300s, comparing raw file before and after. Changed from 1000s of triggers to 3, as expected.

[bieryAtFnal]

LGTM.
I used the change_rate command to set the trigger rate to 0.005 (one per 200 seconds). In a 620-second run, I observed four triggers, which is in the range of what we would expect (one at 0, 200, 400, and 600 seconds into the run).

[eflumerf]

Observed using change_rate_test