Disable sampling of transformed variables from prior_predictive

[purna135]

Addressing #5076

Deleted the code that was added to facilitate sampling from the prior as a starting point for SMC.

[purna135]

Hello, @ricardoV94. I'm still having trouble with make_initial_point_fn. I saw your previous comment but was unable to put it into action. I need your assistance with this.

[codecov]

Codecov Report

Merging #5651 (2170448) into main (7aa520c) will decrease coverage by 4.67%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #5651      +/-   ##
==========================================
- Coverage   87.16%   82.49%   -4.68%     
==========================================
  Files          75       75              
  Lines       13677    13666      -11     
==========================================
- Hits        11922    11274     -648     
- Misses       1755     2392     +637     

Impacted Files	Coverage Δ
pymc/sampling.py	67.45% <ø> (-20.71%)	⬇️
pymc/smc/smc.py	18.47% <0.00%> (-77.92%)	⬇️
pymc/smc/sample_smc.py	16.77% <0.00%> (-66.45%)	⬇️
pymc/func_utils.py	22.50% <0.00%> (-65.00%)	⬇️
pymc/exceptions.py	58.62% <0.00%> (-41.38%)	⬇️
pymc/distributions/simulator.py	46.20% <0.00%> (-41.38%)	⬇️
pymc/backends/base.py	66.66% <0.00%> (-20.52%)	⬇️
pymc/math.py	53.14% <0.00%> (-16.91%)	⬇️
pymc/distributions/mixture.py	80.11% <0.00%> (-14.62%)	⬇️
... and 19 more