Fix checkpoints in schema_abort for slow machines

Parent: compatibility: true, in-mem log sync: false, timestamp in use: true

Parent: Create 5 threads; sleep 10 seconds

CONFIG: test_schema_abort -C -h WT_TEST.schema-abort -T 5 -t 10

Kill child

Open database, run recovery and verify content

Got stable_val 0

records-0: COLLECTION record with key 0 record ts 3 > stable ts 0

records-0: COLLECTION record with key 1 record ts 9 > stable ts 0

records-0: COLLECTION record with key 2 record ts 10 > stable ts 0

records-0: COLLECTION record with key 3 record ts 12 > stable ts 0

...

records-1: COLLECTION record with key 1000004264 record ts 8389 > stable ts 0

records-1: COLLECTION record with key 1000004265 record ts 8391 > stable ts 0

records-2: COLLECTION record with key 2000000000 record ts 4 > stable ts 0

records-3: COLLECTION record with key 3000000000 record ts 5 > stable ts 0

records-4: COLLECTION record with key 4000000000 record ts 7 > stable ts 0

FAIL schema_abort/smoke.sh (exit status: 1)