refactor(3p/nix): Remove remaining prefork-compat type

Removes the verbosity enum, which is no longer actively used anywhere
other than a daemon protocol implementation bit that doesn't actually
work.

Since the verbosity was marked deprecated, this removes one of the
last remaining warnings.

Change-Id: Iaee9d1d6c14b30daac83bb44bcacff32a0e07fb0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1289
Tested-by: BuildkiteCI
Reviewed-by: glittershark <grfn@gws.fyi>

third_party/nix/src/libstore/remote-store.cc

@@ -19,7 +19,6 @@
 #include "libutil/archive.hh"
 #include "libutil/finally.hh"
 #include "libutil/pool.hh"
-#include "libutil/prefork-compat.hh"
 #include "libutil/serialise.hh"
 #include "libutil/util.hh"
 
@@ -167,14 +166,11 @@ void RemoteStore::initConnection(Connection& conn) {
 void RemoteStore::setOptions(Connection& conn) {
   conn.to << wopSetOptions << static_cast<uint64_t>(settings.keepFailed)
           << static_cast<uint64_t>(settings.keepGoing)
-          // TODO(tazjin): Remove the verbosity stuff here.
-          << static_cast<uint64_t>(settings.tryFallback) << compat::kInfo
-          << settings.maxBuildJobs << settings.maxSilentTime
-          << 1u
-          // TODO(tazjin): what behaviour does this toggle remotely?
-          << (settings.verboseBuild ? compat::kError : compat::kVomit)
-          << 0  // obsolete log type
-          << 0  /* obsolete print build trace */
+          << static_cast<uint64_t>(settings.tryFallback)
+          << /* previously: verbosity = */ 0 << settings.maxBuildJobs
+          << settings.maxSilentTime << 1u
+          << /* previously: remote verbosity = */ 0 << 0  // obsolete log type
+          << 0 /* obsolete print build trace */
           << settings.buildCores
           << static_cast<uint64_t>(settings.useSubstitutes);