Revert unnecessary brace and manually set 'NOT_CRAN'

Author: thisisnic

ci/scripts/r_test.sh

@@ -101,7 +101,7 @@ SCRIPT="as_cran <- !identical(tolower(Sys.getenv('NOT_CRAN')), 'true')
     build_args <- '--no-build-vignettes'
   }
 
-  if (!as_cran && (requireNamespace('reticulate', quietly = TRUE)) && reticulate::py_module_available('pyarrow')) {
+  if (!as_cran && requireNamespace('reticulate', quietly = TRUE) && reticulate::py_module_available('pyarrow')) {
       message('Running flight demo server for tests.')
       pid_flight <- sys::exec_background(
           'python',

compose.yaml

@@ -1801,6 +1801,7 @@ services:
       ARROW_R_DEV: ${ARROW_R_DEV}
       ARROW_USE_PKG_CONFIG: "false"
       SKIP_VIGNETTES: "true"
+      NOT_CRAN: "false"
     volumes:
       - .:/arrow:delegated
     command: /arrow/ci/scripts/r_test.sh /arrow