[spec] Better insulation (#4972)

Some combination of Travis and/or older Busted necessitated insufficient insulation.

Follow-up to https://github.com/koreader/koreader/pull/4970

Space condensing carried over; reset at the start of readertoc.

kodev

@@ -758,8 +758,6 @@ OPTIONS:
 
         echo "Running tests in" "${test_path}"
         busted --lua="./luajit" "${opts}" \
-            --no-auto-insulate \
-            --lazy \
             --output=gtest \
             --exclude-tags=notest "${test_path}"
     } && popd || exit
@@ -809,8 +807,6 @@ OPTIONS:
             echo "Running tests in" ${test_path}
             busted --lua="./luajit" \
                 --sort-files \
-                --no-auto-insulate \
-                --lazy \
                 -o "./spec/${target}/unit/verbose_print" \
                 --coverage \
                 --exclude-tags=nocov "${test_path}" || {