Just use releasecheck with tcpdump ci (#2055)

The CI issues we've been having stems from some new tests tcpdump has
for the upcoming 2038 problem. However, these tests will fail with
outdated versions of libpcap that don't support the preprocessor macro
`_TIME_BITS` (Documented in
the-tcpdump-group/tcpdump#1147)

**Tcpdump's fixed the issue when running release-check:
the-tcpdump-group/tcpdump@0546e6a.
Release-check already runs with check and runs all the tests, but with a
more defined process.**
Since upstream's just running release-check to encapsulate everything, I
think we can just run release-check here to get rid of CI issues.

### Call-outs:
N/A

### Testing:
CI

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license and the ISC license.

tests/ci/integration/run_tcpdump_integration.sh

@@ -42,7 +42,6 @@ function tcpdump_build() {
 }
 
 function tcpdump_run_tests() {
-  make -j "$NUM_CPU_THREADS" check
   make -j "$NUM_CPU_THREADS" releasecheck
 }