test: relax quota for tests on machines with small page size

8a8589038c ("test: increase quota for tests to 6GB") increased
the quota for tests from 2GB to 6GB. I later found that the increased
requirement is related to the page size: Address Sanitizer allocates
at least a page per object, and so if the page size is larger the
memory requirement is also larger.

Make use of this by only increasing the quota if the page size
is greater than 4096 (I've only seen 4096 and 65536 in the wild).
This allows greater parallelism when the page size is small.

Closes #8371

test.py

@@ -513,7 +513,7 @@ def parse_cmd_line():
     """ Print usage and process command line options. """
     all_modes = ['debug', 'release', 'dev', 'sanitize']
     sysmem = os.sysconf('SC_PAGE_SIZE') * os.sysconf('SC_PHYS_PAGES')
-    testmem = 6e9
+    testmem = 6e9 if os.sysconf('SC_PAGE_SIZE') > 4096 else 2e9
     cpus_per_test_job = 1
     default_num_jobs_mem = ((sysmem - 4e9) // testmem)
     default_num_jobs_cpu = multiprocessing.cpu_count() // cpus_per_test_job