[CI] Remove macos-notest-ios bot

[CI] Remove macos-notest-ios bot

Not sure what ancient compiler it is (gcc 4.2?), but didn't like hb_zip SFINAE
apparently:

In file included from /Users/distiller/project/src/hb-aat-layout.cc:28:
In file included from /Users/distiller/project/src/hb-open-type.hh:32:
In file included from /Users/distiller/project/src/hb.hh:642:
/Users/distiller/project/src/hb-iter.hh:364:1: note: candidate template ignored: substitution failure [with A = OT::Coverage, B = OT::OffsetArrayOf<OT::ChainRuleSet>]: non-type template argument does not refer to any declaration
hb_zip (const A& a, const B &b)
^
In file included from /Users/distiller/project/src/hb-aat-layout.cc:37:
In file included from /Users/distiller/project/src/hb-aat-layout-kerx-table.hh:31:
In file included from /Users/distiller/project/src/hb-kern.hh:32:
/Users/distiller/project/src/hb-ot-layout-gpos-table.hh:725:20: error: no matching function for call to 'hb_zip'
    for (auto it = hb_zip (this+coverage, pairSet)
                   ^~~~~~

Not going to try to appease.