Use the default retention time for CI artifacts

The instance-wide GitLab CI artifact retention time was changed to 1 day
up from the previous value of 12 hours. Remove our explicit overrides
for 1 day artifact retention time, as it is the default now.

Previously, most of our jobs had overrides for 1 day retention, while
some of our jobs used the default 12 hours. This discrepancy could be
quite impractical at times.

.gitlab-ci.yml

@@ -218,7 +218,6 @@ stages:
     - autoreconf -fi
   artifacts:
     untracked: true
-    expire_in: "1 day"
 
 .configure: &configure
     - ${CONFIGURE}
@@ -287,7 +286,6 @@ stages:
       artifacts: true
   artifacts:
     untracked: true
-    expire_in: "1 day"
     when: always
 
 .setup_interfaces: &setup_interfaces
@@ -321,7 +319,6 @@ stages:
   <<: *system_test_common
   artifacts:
     untracked: true
-    expire_in: "1 day"
     when: always
     reports:
       junit: junit.xml
@@ -330,7 +327,6 @@ stages:
   <<: *system_test_common
   artifacts:
     untracked: true
-    expire_in: "1 day"
     when: always
 
 .system_test_tsan: &system_test_tsan_job
@@ -343,7 +339,6 @@ stages:
       "$PYTHON" bin/tests/convert-trs-to-junit.py . > "$CI_PROJECT_DIR"/junit.xml
   artifacts:
     untracked: true
-    expire_in: "1 day"
     when: always
     reports:
       junit: junit.xml
@@ -367,7 +362,6 @@ stages:
   <<: *unit_test_common
   artifacts:
     untracked: true
-    expire_in: "1 day"
     when: always
     reports:
       junit: junit.xml
@@ -376,7 +370,6 @@ stages:
   <<: *unit_test_common
   artifacts:
     untracked: true
-    expire_in: "1 day"
     when: always
 
 .unit_test_tsan: &unit_test_tsan_job
@@ -388,7 +381,6 @@ stages:
       "$PYTHON" bin/tests/convert-trs-to-junit.py . > "$CI_PROJECT_DIR"/junit.xml
   artifacts:
     untracked: true
-    expire_in: "1 day"
     when: always
     reports:
       junit: junit.xml
@@ -418,7 +410,6 @@ stages:
     exclude:
       - bind-qa/bind9/respdiff/rspworkdir/data.mdb # Exclude a 10 GB file.
     untracked: true
-    expire_in: "1 day"
     when: always
 
 ### Job Definitions
@@ -450,7 +441,6 @@ misc:
   artifacts:
     paths:
       - checklibs.out
-    expire_in: "1 day"
     when: on_failure
 
 black:
@@ -749,7 +739,6 @@ scan-build:
   artifacts:
     paths:
       - scan-build.reports/
-    expire_in: "1 day"
     when: on_failure
 
 # Jobs for strict OpenSSL 3.x (no deprecated) GCC builds on Debian "sid" (amd64)