Merge #16060: Bury bip9 deployments

e78aaf41f4 [docs] Add release notes for burying bip 9 soft fork deployments (John Newbery)
8319e738f9 [tests] Add coverage for the content of getblockchaininfo.softforks (James O'Beirne)
0328dcdcfc [Consensus] Bury segwit deployment (John Newbery)
1c93b9b31c [Consensus] Bury CSV deployment height (John Newbery)
3862e473f0 [rpc] Tidy up reporting of buried and ongoing softforks (John Newbery)

Pull request description:

  This hardcodes CSV and segwit activation heights, similar to the BIP 90 buried deployments for BIPs 34, 65 and 66.

  CSV and segwit have been active for over 18 months. Hardcoding the activation height is a code simplification, makes it easier to understand segwit activation status, and reduces technical debt.

  This was originally attempted by jl2012 in #11398 and again by me in #12360.

ACKs for top commit:
  ajtowns:
    ACK e78aaf41f4 ; checked diff to previous acked commit, checked tests still work
  ariard:
    ACK e78aaf4, check diff, run the tests again and successfully activated csv/segwit heights on mainnet as expected.
  MarcoFalke:
    ACK e78aaf41f4 (still didn't check if the mainnet block heights are correct, but the code looks good now)

Tree-SHA512: 7e951829106e21a81725f7d3e236eddbb59349189740907bb47e33f5dbf95c43753ac1231f47ae7bee85c8c81b2146afcdfdc11deb1503947f23093a9c399912

test/functional/test_framework/util.py

@@ -335,9 +335,9 @@ def delete_cookie_file(datadir, chain):
         logger.debug("Deleting leftover cookie file")
         os.remove(os.path.join(datadir, chain, ".cookie"))
 
-def get_bip9_status(node, key):
-    info = node.getblockchaininfo()
-    return info['bip9_softforks'][key]
+def softfork_active(node, key):
+    """Return whether a softfork is active."""
+    return node.getblockchaininfo()['softforks'][key]['active']
 
 def set_node_times(nodes, t):
     for node in nodes: