An earlier version of #16546 used both --with-boost-process and --enable-external-signer, which was simplified to only use the latter. However I forgot to update CI, so the external signer tests were not run.
This reverts the changes made in merge commit
1b307613604883daea4913a65da30ae073c9dc4d:
This reverts commit b919efadff3d0393f4a8c3c1dc735f7ac5c665bb.
This reverts commit d54f64c6c700be0604190f52c84fc5f1cdd9f02f.
This reverts commit 787f40668dc15980c3d6de028d7950c08175d84a.
This reverts commit d6306466626635e6fee44385e6a688c8dc118eb5.
This reverts commit e6e44eedd56ecaf59f3fabf8e07ab7dee0ddb1b6.