cloud_roles: run setenv on reactor thread

This patch changes boost tests that call setenv so that they run on a
reactor thread rather than the main thread. Without this change we end
up hitting this assertion:

  test_cloud_roles_rpunit:
  /home/nwatkins/src/redpanda/vbuild/release/clang/v_deps_build/seastar-prefix/src/seastar/src/core/memory.cc:986:
  void seastar::memory::cpu_pages::shrink(void *, size_t): Assertion
  `object_cpu_id(ptr) == cpu_id' failed.

NOTE: it is not clear that this really fixes the issue, but at least the
issue doesn't appear to happen anymore. According to this seastar-dev
thread setenv is interacting with global state and the realloc that it
performs may involve some mixture of memory accessed by different cores,
before/after the low-level allocators are swapped out by seastar.

   https://groups.google.com/g/seastar-dev/c/hSdTKn05Ei8/m/cH4bFvmEAgAJ

Overall it seems like we might want to consider getting rid of setenv
calls. There is only one in Redpanda proper (krb5 stuff).

Signed-off-by: Noah Watkins <[email protected]>

Author: dotnwat

src/v/cloud_roles/tests/categorization_tests.cc

@@ -13,12 +13,11 @@
 
 #include <seastar/core/abort_source.hh>
 #include <seastar/core/gate.hh>
-
-#include <boost/test/unit_test.hpp>
+#include <seastar/testing/thread_test_case.hh>
 
 inline ss::logger test_log("test"); // NOLINT
 
-BOOST_AUTO_TEST_CASE(test_refresh_client_built_according_to_source) {
+SEASTAR_THREAD_TEST_CASE(test_refresh_client_built_according_to_source) {
     ss::abort_source as;
     cloud_roles::aws_region_name region{"atlantis"};
     {
@@ -66,7 +65,7 @@ BOOST_AUTO_TEST_CASE(test_refresh_client_built_according_to_source) {
       std::invalid_argument);
 }
 
-BOOST_AUTO_TEST_CASE(
+SEASTAR_THREAD_TEST_CASE(
   test_credential_applier_built_according_to_credential_kind) {
     {
         cloud_roles::gcp_credentials gc{};

src/v/cloud_roles/tests/env_override_tests.cc

@@ -11,11 +11,12 @@
 #include "cloud_roles/refresh_credentials.h"
 
 #include <seastar/core/gate.hh>
+#include <seastar/testing/thread_test_case.hh>
 #include <seastar/util/defer.hh>
 
 #include <boost/test/unit_test.hpp>
 
-BOOST_AUTO_TEST_CASE(test_override_address) {
+SEASTAR_THREAD_TEST_CASE(test_override_address) {
     ss::abort_source as;
     cloud_roles::aws_region_name region{"atlantis"};
 
@@ -39,7 +40,7 @@ BOOST_AUTO_TEST_CASE(test_override_address) {
     }
 }
 
-BOOST_AUTO_TEST_CASE(test_override_address_fails_on_bad_address) {
+SEASTAR_THREAD_TEST_CASE(test_override_address_fails_on_bad_address) {
     ss::abort_source as;
     cloud_roles::aws_region_name region{"atlantis"};