captureStdoutStderr*: move to Hydra::Helper::Exec which helps avoid some environment variable fixation problems

t/Hydra/Controller/Jobset/channel.t

@@ -6,13 +6,13 @@ use IO::Uncompress::Bunzip2 qw(bunzip2);
 use Archive::Tar;
 use JSON::MaybeXS qw(decode_json);
 use Data::Dumper;
+use Hydra::Helper::Exec;
 my %ctx = test_init(
   use_external_destination_store => 0
 );
 
 require Hydra::Schema;
 require Hydra::Model::DB;
-require Hydra::Helper::Nix;
 
 use Test2::V0;
 require Catalyst::Test;
@@ -47,7 +47,7 @@ $tar->extract_file("channel/default.nix", $defaultnix);
 
 print STDERR $tar->get_content("channel/default.nix");
 
-(my $status, my $stdout, my $stderr) = Hydra::Helper::Nix::captureStdoutStderr(5, "nix-env", "--json", "--query", "--available", "--attr-path", "--file", $defaultnix);
+(my $status, my $stdout, my $stderr) = captureStdoutStderr(5, "nix-env", "--json", "--query", "--available", "--attr-path", "--file", $defaultnix);
 is($stderr, "", "Stderr should be empty");
 is($status, 0, "Querying the packages should succeed");
 

t/Hydra/Plugin/RunCommand/basic.t

@@ -13,6 +13,8 @@ my %ctx = test_init(
 
 require Hydra::Schema;
 require Hydra::Model::DB;
+require Hydra::Helper::Nix;
+
 
 use Test2::V0;
 

t/lib/CliRunners.pm

@@ -2,35 +2,15 @@ use warnings;
 use strict;
 
 package CliRunners;
+use Hydra::Helper::Exec;
 our @ISA = qw(Exporter);
 our @EXPORT = qw(
-    captureStdoutStderr
-    captureStdoutStderrWithStdin
     evalFails
     evalSucceeds
     runBuild
     sendNotifications
 );
 
-
-sub captureStdoutStderr {
-    # "Lazy"-load Hydra::Helper::Nix to avoid the compile-time
-    # import of Hydra::Model::DB. Early loading of the DB class
-    # causes fixation of the DSN, and we need to fixate it after
-    # the temporary DB is setup.
-    require Hydra::Helper::Nix;
-    return Hydra::Helper::Nix::captureStdoutStderr(@_)
-}
-
-sub captureStdoutStderrWithStdin {
-    # "Lazy"-load Hydra::Helper::Nix to avoid the compile-time
-    # import of Hydra::Model::DB. Early loading of the DB class
-    # causes fixation of the DSN, and we need to fixate it after
-    # the temporary DB is setup.
-    require Hydra::Helper::Nix;
-    return Hydra::Helper::Nix::captureStdoutStderrWithStdin(@_)
-}
-
 sub evalSucceeds {
     my ($jobset) = @_;
     my ($res, $stdout, $stderr) = captureStdoutStderr(60, ("hydra-eval-jobset", $jobset->project->name, $jobset->name));

t/lib/Setup.pm

@@ -8,12 +8,11 @@ use File::Temp;
 use File::Path qw(make_path);
 use File::Basename;
 use Cwd qw(abs_path getcwd);
+use Hydra::Helper::Exec;
 use CliRunners;
 
 our @ISA = qw(Exporter);
 our @EXPORT = qw(
-    captureStdoutStderr
-    captureStdoutStderrWithStdin
     createBaseJobset
     createJobsetWithOneInput
     evalFails

t/queue-runner/build-locally-with-substitutable-path.t

@@ -3,10 +3,14 @@ use warnings;
 use Setup;
 use Data::Dumper;
 use Test2::V0;
+use Hydra::Helper::Exec;
+
 my $ctx = test_context(
     use_external_destination_store => 1
 );
 
+require Hydra::Helper::Nix;
+
 # This test is regarding https://github.com/NixOS/hydra/pull/1126
 #
 # A hydra instance was regularly failing to build derivations with:

t/scripts/hydra-create-user.t

@@ -2,6 +2,7 @@ use strict;
 use warnings;
 use Setup;
 use Test2::V0;
+use Hydra::Helper::Exec;
 
 my $ctx = test_context();
 my $db = $ctx->db();

t/scripts/hydra-init.t

@@ -2,6 +2,7 @@ use feature 'unicode_strings';
 use strict;
 use warnings;
 use Setup;
+use Hydra::Helper::Exec;
 
 my %ctx = test_init();
 

t/scripts/hydra-send-stats.t

@@ -2,6 +2,7 @@ use feature 'unicode_strings';
 use strict;
 use warnings;
 use Setup;
+use Hydra::Helper::Exec;
 
 my %ctx = test_init();
 

t/scripts/hydra-update-gc-roots/update-gc-roots.t

@@ -3,6 +3,7 @@ use strict;
 use warnings;
 use Setup;
 use Test2::V0;
+use Hydra::Helper::Exec;
 
 my $ctx = test_context();
 my $builds = $ctx->makeAndEvaluateJobset(