Strip whitespace between field-name and the :

[bryancall]

We MUST strip whitespace between field-name and the : on servers responses.

This is the PR that changed how we handle spaces: #6794

08:49:30 bart:(9.0.x)~/dev/apache/trafficserver/build-Linux$ tail -1 /usr/local/etc/trafficserver/remap.config
map /  https://iqconnect.house.gov/
08:52:16 bart:(9.0.x)~/dev/apache/trafficserver/build-Linux$ curl -D - -so /dev/null http://127.0.0.1:8080/iqextranet/Customers/VA99LD/cherry-blossom-facts.jpg | grep Protection
X-XSS-Protection : 1; mode=block
X-XSS-Protection: 1

[bryancall]

https://tools.ietf.org/html/rfc7230#section-3.2.4

No whitespace is allowed between the header field-name and colon. In
the past, differences in the handling of such whitespace have led to
security vulnerabilities in request routing and response handling. A
server MUST reject any received request message that contains
whitespace between a header field-name and colon with a response code
of 400 (Bad Request). A proxy MUST remove any such whitespace from a
response message before forwarding the message downstream.

[bryancall]

With #6794 reverted I get:

09:54:53 bart:(9.0.x)~/dev/apache/trafficserver/build-Linux$ curl -D - -so /dev/null http://127.0.0.1:8080/iqextranet/Customers/VA99LD/cherry-blossom-facts.jpg
HTTP/1.1 502 Invalid HTTP Response