Remove TAP test for timeline lookup race with logical decoding on standbys

Remove TAP test for timeline lookup race with logical decoding on standbys

16b89ff04839 has introduced this test, but I have missed that the script
should check for the existence of the test module injection_points.
This requirement has been added by 105b2cb33617 in v18 and newer
branches.

Let's just remove the test on v17.  There is still coverage in v18 and
HEAD, that should be good enough.

Per reports from the buildfarm.

Discussion: https://postgr.es/m/aiqFjzGHpnYFP-Gm@paquier.xyz
Backpatch-through: 17 (only)