strongswan: do not use config_foreach named section globals

strongswan: do not use config_foreach named section globals

In a previous commit, the anonymous 'ipsec' section was changed to a named
section called 'globals'. The reason for this is that this is where the
'strongswan.conf' configuration option are saved. This should only occur
once. Since only one strongswan service can be running on the system.

Therefore, in this commit, the 'config_foreach' loop is removed and
the section is permanently set to 'globals'.

This commit does not change the function and is a preparatory commit.
Assuming there is a global section named 'ipsec'.

Signed-off-by: Florian Eckert <redacted>