Update CHAMPS perf plots' start date (chapel-lang#23495)

This PR is a quick adjustment for the apollo-hdr CHAMPS performance
plots.

[Trivial, not reviewed]

util/cron/common-champs.bash

@@ -50,7 +50,7 @@ source $CWD/common-perf.bash
 CHAMPS_PERF_DIR=${CHAMPS_PERF_DIR:-$COMMON_DIR/NightlyPerformance/champs}
 export CHPL_TEST_PERF_CONFIG_NAME='16-node-apollo-hdr'
 export CHPL_TEST_PERF_DIR=$CHAMPS_PERF_DIR/$CHPL_TEST_PERF_CONFIG_NAME
-export CHPL_TEST_PERF_START_DATE=01/21/22
+export CHPL_TEST_PERF_START_DATE=09/14/23
 
 # Run champs correctness and performance testing
 export CHPL_NIGHTLY_TEST_DIRS=studies/champs/
@@ -86,6 +86,8 @@ export GASNET_IBV_SPAWNER=ssh
 
 export CHPL_TEST_PERF_CONFIGS="llvm:v,c-backend"  # v: visible by def
 
+nightly_args="${nightly_args} -no-buildcheck -startdate $CHPL_TEST_PERF_START_DATE"
+
 function sync_graphs() {
   $CHPL_HOME/util/cron/syncPerfGraphs.py $CHPL_TEST_PERF_DIR/html/ champs/$CHPL_TEST_PERF_CONFIG_NAME
 }

util/cron/test-perf.cray-cs-hdr.champs.c-backend.bash

@@ -13,6 +13,6 @@ source $CWD/common-c-backend.bash
 
 export CHPL_TARGET_CPU=none
 
-$CWD/nightly -cron ${nightly_args} -no-buildcheck
+$CWD/nightly -cron ${nightly_args}
 
 sync_graphs

util/cron/test-perf.cray-cs-hdr.champs.llvm.bash

@@ -12,6 +12,6 @@ source $CWD/common-champs.bash
 
 export CHPL_TARGET_CPU=none
 
-$CWD/nightly -cron ${nightly_args} -no-buildcheck
+$CWD/nightly -cron ${nightly_args}
 
 sync_graphs