Use --no-loop for new calls of pg_receivewal --endpos in TAP tests

Use --no-loop for new calls of pg_receivewal --endpos in TAP tests

Those tests are not designed to fail, but if they do, like on some cases
for Windows because of ZLIB (?), they could remain stuck.  Using
--no-loop makes the test fail immediately.  The oldest test with
--endpos already did that.

Those tests have been added in ffc9dda.

Reviewed-by: Andrew Dunstan
Discussion: https://postgr.es/m/ec093ff1-a53c-0091-46a2-4537354b0dd4@dunslane.net