Fix configure arg shell quoting for SANITIZE (#999)

Author: vector-of-bool

.evergreen/compile-unix.sh

@@ -200,7 +200,8 @@ esac
 if [ "darwin" = "$OS" -a "arm64" = "$MARCH" ]; then
    CONFIGURE_FLAGS="$CONFIGURE_FLAGS -DCMAKE_OSX_ARCHITECTURES=arm64"
 fi
-CONFIGURE_FLAGS="$CONFIGURE_FLAGS \"-DMONGO_SANITIZE=${SANITIZE}\""
+
+CONFIGURE_FLAGS="$CONFIGURE_FLAGS -DMONGO_SANITIZE=$SANITIZE"
 
 if ! python3 build/mongodl.py --test -C csfle -V 5.3.1 -o . > /dev/null; then
    echo "No csfle detected for this platform. Disabling MONGOC_TEST_USE_CSFLE."