Default to anchors and remove automatic channel acceptance

[elnosh]

Closes #4337

Changes negotiate_anchors_zero_fee_htlc_tx default to true and removes the manually_accept_inbound_channels config option.

Edit: Left the tests with default to non-anchor

[ldk-reviews-bot]

👋 Thanks for assigning @wpaulino as a reviewer!
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Once they submit their review, I'll check if a second reviewer would be helpful.

[TheBlueMatt]

Changing the negotiate_anchors_zero_fee_htlc_tx default to true in the tests causes +100 test failures

Hmm, can you ask claude to change those to use the test_default_config() thing? Our test config default has diverged somewhat from our actual default config for reasons like this but that's okay...

[codecov]

Codecov Report

❌ Patch coverage is 81.39535% with 16 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.09%. Comparing base (7fe3268) to head (b1ee9e3).

Files with missing lines	Patch %	Lines
lightning/src/ln/channelmanager.rs	70.45%	12 Missing and 1 partial ⚠️
lightning/src/ln/functional_test_utils.rs	90.62%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##           main    #4354       +/-   ##
=========================================
+ Coverage      0   86.09%   +86.09%     
=========================================
  Files         0      156      +156     
  Lines         0   102450   +102450     
  Branches      0   102450   +102450     
=========================================
+ Hits          0    88202    +88202     
- Misses        0    11754    +11754     
- Partials      0     2494     +2494     

Flag	Coverage Δ
tests	86.09% <81.39%> (?)

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