redirect visitors based on geolocation - update host condition

[ys2843]

Description

This is a fix for #18431 . The rewrite rule is not redirecting users because of the tight host filter rule. Update the rewrite condition to not only match mxnet.apache.org, but reverse it to match all hostname except mxnet.cdn.apache.org.

According to Apache Intra team's response,

Try removing the following condition:
RewriteCond %{HTTP_HOST} mxnet.apache.org
Most of your visits go to mxnet.incubator.apache.org

Because we don't know how Apache's server is configured, remove the whole condition could possibly import looping. To safely fix this problem we can first test the updated rewrite rule.

[mxnet-bot]

Hey @ys2843 , Thanks for submitting the PR
All tests are already queued to run once. If tests fail, you can trigger one or more tests again with the following commands:

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[szha]

how are you testing it

[ys2843]

how are you testing it

By using speedtest websites which have Chinese server, we can see redirect in the result. Test with any one of the following:

• https://www.boce.com/ (Chinese speed test website, simply copy url to test)
• https://www.webpagetest.org/ (Choose Beijing as location then test)

I created this host to test the redirect rules, it uses the same rules as this PR

• http://ec2-34-219-134-42.us-west-2.compute.amazonaws.com/

RewriteCond %{ENV:GEOIP_COUNTRY_CODE} ^CN$
RewriteCond %{HTTP_HOST} !cdn
RewriteRule ^(.*) https://mxnet.cdn.apache.org%{REQUEST_URI} [R,NC,L]

Please see this test result: https://www.webpagetest.org/result/200602_1B_4efffb1027dd235c69766571b04d658e/1/details/#waterfall_view_step1