faster CIs (#13803)
* ttables: smaller table, 5x speedup
* thavlak: less iterations, less loops; 30% speedup
* tasyncclosestall: shorter timeout; 35% speedup
* gcleak4: less iterations, 2x speedup
* ttimes: remove deprecated stuff
* tdangerisrelease: remove cpp backend, 3x speedup
* tfrexp1: smaller range, 2x speedup
* trtree: fix warnings, less iterations, 6x speedup
* tasyncawait_cyclebreaker: smaller swarm size; 2x speedup
* trealloc: smaller number of iterations; 10x speedup
* towned_binary_tree: less iterations, 4x speedup
* tclosure: remove unused code, less iterations; 2x speedup
* twaitany: less durations; 1.4x speedup
* tasync_misc: less iterations, 2x speedup
* t8535: smaller sleep, 1.5x speedup
* tmanyjoin: smaller sleep, 2x speedup
* t12221: shorter sleeps, removed two slower tests; 1.6x speedup
* tfuturestream: smaller sleep; 1.5x speedup
* growobjcrash: less iterations; 2x speedup
* ttryrecv: smaller sleep; 1.5x speedup
* treusetvar: less threads; 2x speedup
* delete tthreadanalysis2, basically a duplicate of tthreadanalysis
* t7758: less iterations, 1.5x speedup
* tasyncawait: smaller swarm, less messages; 1.5x speedup
* tjsandnativeasync: smaller sleep, 1.5x speedup
* tpendingcheck: smaller sleep, 1.5x speedup
* remove rodfiles test category
* move tseq from its own category to 'collections' category
* remove unneeded tests and helpers from 'assert' category
* stdlib: merge tbitops2 into tbitops
* remove 'trepr2' from 'stdlib' cat
* merge 'tstreams' into one file
* remove 'tinefficient_const_table' from 'ccbugs' cat
* merge 'tcollections_to_string' into 'tcollections'
* tblocking_channel: smaller sleep, small speedup
* tconvexhull: less iterartions; 1.2x speedup
* merge 'tdeepcopy2' into 'tdeepcopy'
* merge 'tdisjoint_slice2' into 'tdisjoint_slice1'
* tmissing_deepcopy: smaller sequence
* tsendtwice: smaller arrays; 5x speedup
* remove 'tindexerrorformatbounds'
* disable multimethod tests
* remove 'gc:none' and 'refc' without 'd:useRealtimeGC' from gc tests
* koch.nim: bootstrap just with '-d:release', no need for 'csource'
* add github workflow for documentation
* testament: no need for 8 sub-second decimals
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