header_rewrite: remove RemapAPI-only restriction for PATH conditions

Segfault in PATH condition was already fixed in 236c52cf:
    "TS-2316: header_rewrite: fixed segfaults in ConditionPath::append_value()"

Submitted by: Alexey Ivanov <aivanov@linkedin.com>
Sponsored by: LinkedIn
Merge branch 'master' of https://github.com/SaveTheRbtz/trafficserver