Remove redundant final_cltv_delta param from get_route

[valentinewallace]

PaymentParameters already includes this value.

This set us up to better support route blinding, since there is no known final_cltv_delta when paying to a blinded route.

[codecov-commenter]

Codecov Report

Patch coverage: 98.11% and project coverage change: -0.01 ⚠️

Comparison is base (4f806f5) 91.57% compared to head (cae41c1) 91.56%.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2239      +/-   ##
==========================================
- Coverage   91.57%   91.56%   -0.01%     
==========================================
  Files         104      104              
  Lines       51782    51781       -1     
  Branches    51782    51781       -1     
==========================================
- Hits        47417    47413       -4     
- Misses       4365     4368       +3     

Impacted Files	Coverage Δ
lightning/src/routing/router.rs	95.09% <97.50%> (-0.01%)	⬇️
lightning/src/ln/functional_test_utils.rs	92.79% <100.00%> (ø)
lightning/src/ln/functional_tests.rs	98.25% <100.00%> (ø)
lightning/src/ln/onion_route_tests.rs	98.26% <100.00%> (ø)
lightning/src/ln/payment_tests.rs	97.57% <100.00%> (ø)
lightning/src/ln/priv_short_conf_tests.rs	97.59% <100.00%> (ø)
lightning/src/ln/shutdown_tests.rs	98.05% <100.00%> (ø)

... and 1 file with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.

[TheBlueMatt]

Thanks!