Upstream changes in WP_Meta_Query break BP_Groups_Group::get_meta_query_sql() parsing

[boonebgorges]

See ​https://core.trac.wordpress.org/ticket/25538#comment:23 for background.

We do some ugly parsing of WP_Meta_Query's SQL to make it compatible with the JOIN format of the groups query. To salvage the current logic, we'll need an upstream fix, but in the meantime I'm going to apply some fixes to make our parsing somewhat less brittle (eg, reliant on line breaks).

[boonebgorges]

In 8476:

Clean up parsed meta_query clauses before performing preg_replaces() in BP_Groups_Group::get_meta_query_sql()

Some weaknesses in parsing were exposed by upstream changes. See
​https://core.trac.wordpress.org/ticket/25538#comment:23.

This changeset makes the parsing less brittle by relying less on the details of
the line breaks introduced by WP into the query string.

See #5682

[boonebgorges]

The kind folks at WP have put in a fix that resolves this issue.