[nix] don't use experimental features for corenlp nix call

Also, update Dockerfile with patched `nix.conf`
4 jobs for 483-dev-corenlp-in-nix-flake in 47 minutes and 7 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Cabal
passed #18644
cabal

00:23:02

 
  Stack
passed #18645
stack

00:03:51

 
  Bench
manual #18646
allowed to fail manual
bench
 
  Test
failed #18647
test

00:20:13

 
Name Stage Failure
failed
test Test
Test suite garg-test-hspec: FAIL
Test suite logged to:
/builds/gargantext/haskell-gargantext/dist-newstyle/build/x86_64-linux/ghc-9.6.6/gargantext-0.0.7.4.7/t/garg-test-hspec/opt/test/gargantext-0.0.7.4.7-garg-test-hspec.log
0 of 1 test suites (0 of 1 test cases) passed.
Error: [Cabal-7125]
Tests failed for test:garg-test-hspec from gargantext-0.0.7.4.7.

Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1