build: make scripts for remote testing usable

This updates `scripts/remote_tests_{rust,python}.sh`.
The scripts were previously used to run tests
from CI on remote faster machine,
but they are still usable to run tests remotely
e.g. from a laptop that is on battery.

scripts/remote_tests_rust.sh

@@ -1,29 +1,25 @@
-#!/bin/bash 
+#!/usr/bin/env bash
+set -euo pipefail
 
-BUILD_ID=${1:?specify build ID}
-
-SSHTARGET=${SSHTARGET-ci@b1.delta.chat}
-BUILDDIR=ci_builds/$BUILD_ID
-
-set -e
+if ! test -v SSHTARGET; then
+        echo >&2 SSHTARGET is not set
+        exit 1
+fi
+BUILDDIR=ci_builds/chatmailcore
 
 echo "--- Copying files to $SSHTARGET:$BUILDDIR"
 
-ssh -oBatchMode=yes -oStrictHostKeyChecking=no $SSHTARGET mkdir -p "$BUILDDIR"
-git ls-files >.rsynclist
-rsync --delete --files-from=.rsynclist -az ./ "$SSHTARGET:$BUILDDIR"
+rsync -az --delete --mkpath --files-from=<(git ls-files) ./ "$SSHTARGET:$BUILDDIR"
 
 echo "--- Running Rust tests remotely"
 
-ssh $SSHTARGET <<_HERE
+ssh -oBatchMode=yes -- "$SSHTARGET" <<_HERE
     set +x -e
     # make sure all processes exit when ssh dies
     shopt -s huponexit
-    export RUSTC_WRAPPER=\`which sccache\`
+    export RUSTC_WRAPPER=\`command -v sccache\`
     cd $BUILDDIR
-    export TARGET=x86_64-unknown-linux-gnu
-    export RUSTC_WRAPPER=sccache
 
-    bash scripts/run-rust-test.sh
+    cargo nextest run
 _HERE