services/netdata: add cacheDir option

[ivankovnatsky]

For me netdata could not start:

time=2025-03-18T21:27:21.023+02:00 comm=netdata source=daemon level=info errno="2, No such file or directory" tid=257369  msg="CONFIG: cannot load cloud config '/var/lib/netdata/cloud.d/cloud.conf'. Running with internal defaults."
time=2025-03-18T21:27:21.024+02:00 comm=netdata source=daemon level=alert errno="2, No such file or directory" tid=257369  msg="Cannot create required directory '/var/cache/netdata'"
0   netdata                             0x0000000104845cb0 netdata_logger_fatal + 356
1   netdata                             0x00000001044d8734 verify_or_create_required_directory + 84
2   netdata                             0x00000001044d718c set_global_environment + 524
3   netdata                             0x00000001044db294 netdata_main + 1920
4   netdata                             0x00000001044dd178 main + 12
5   dyld                                0x0000000184394274 start + 2840