mgcp_test: fix get_conn_id_from_response() CI length

This function is set on conn ID length of 32 characters. Make it detect a
shorter length also when parsing 'o=-' headers. Before, this failed to
recognize a space as the end of the conn ID, now sees any non-hex char as end.

Related: OS#3507
Change-Id: I762c273bac172acb6d0aae6ea6267603ab654cbf
1 file changed