[ObjC] increase Basic Tests C/C++ MacOS jobs (to 16)

[copybara-service]

Currently, the test is still consistently timing out (after increasing the job count from 4 -> 8 in #36190)

[HannahShiSFB]

Looks like the box only has 4 cores and 16G ram, I guess that's why increase jobs didn't help last time and likely won't work either with this PR.

Is it possible that we schedule MacOS jobs to some larger machines?

+++ sysctl -n machdep.cpu.brand_string
++ echo 'CPU: GenuineIntel x86_64 Family 6 Model Intel(R) Core(TM) i7-8700B CPU @ 3.20GHz'
CPU: GenuineIntel x86_64 Family 6 Model Intel(R) Core(TM) i7-8700B CPU @ 3.20GHz
+++ sysctl -n hw.ncpu
++ echo 'CPU Cores: 4'
CPU Cores: 4
+++ sysctl -n hw.memsize
++ echo 'Memory: 17179869184'
Memory: 17179869184

[sampajano]

Looks like the box only has 4 cores and 16G ram, I guess that's why increase jobs didn't help last time and likely won't work either with this PR.

Aha you're right! It didn't seem to help indeed.. As the test again timed out here.. 😅

I'll drop this PR for now.. (And the better solution is probably to split the dbg and opt test as you've suggested earlier).

Is it possible that we schedule MacOS jobs to some larger machines?

Seems like that's not an option at this moment :)

[sampajano]

Dropping this PR as it didn't help :)

Will try out the idea to split the opt and dbg tests next :)