Update OpAMP store effective configuration file permissions

[portertech]

Remote configuration files created by agent are created with default permissions and are readable by all users in the system. This potentially may contain some secrets.

Read permission for these files should be assigned only to files owner (0600 permission)

sumologic-otel-collector/pkg/extension/opampextension/opamp_agent.go

Line 377 in d808404

f, err := os.Create(p)

$ ls -al /etc/otrm/
total 12
drwxr-xr-x  2 root root 4096 Nov 21 14:21 .
drwxr-xr-x 95 root root 4096 Nov 21 13:07 ..
-rw-r--r--  1 root root 1325 Nov 21 14:21 00000000000004DF.yaml