[BlockSTM] Better naming for execution task

[danielxiangzl]

Description

This PR does some trivial renaming for better clarity. Adding ExecutionTaskType to distinguish the actual execution task from the wake-up task.
Previously the ExecutionTask in the scheduler contains Option<DependencyCondvar> to distinguish the actual execution task from the fake execution task that just wakes up the earlier pending execution task via DependencyCondvar.

Test Plan

Existing tests.

[github-actions]

✅ Forge suite compat success on testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> ee23d70eb9947415b6285c27cee498eb5b7ad7fe

Compatibility test results for testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> ee23d70eb9947415b6285c27cee498eb5b7ad7fe (PR)
1. Check liveness of validators at old version: testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b
compatibility::simple-validator-upgrade::liveness-check : committed: 8885 txn/s, latency: 3788 ms, (p50: 3700 ms, p90: 5400 ms, p99: 6200 ms), latency samples: 302100
2. Upgrading first Validator to new version: ee23d70eb9947415b6285c27cee498eb5b7ad7fe
compatibility::simple-validator-upgrade::single-validator-upgrade : committed: 4586 txn/s, latency: 7043 ms, (p50: 7100 ms, p90: 9900 ms, p99: 10600 ms), latency samples: 178860
3. Upgrading rest of first batch to new version: ee23d70eb9947415b6285c27cee498eb5b7ad7fe
compatibility::simple-validator-upgrade::half-validator-upgrade : committed: 4390 txn/s, latency: 7347 ms, (p50: 8100 ms, p90: 8900 ms, p99: 9600 ms), latency samples: 166820
4. upgrading second batch to new version: ee23d70eb9947415b6285c27cee498eb5b7ad7fe
compatibility::simple-validator-upgrade::rest-validator-upgrade : committed: 6470 txn/s, latency: 5229 ms, (p50: 5100 ms, p90: 7800 ms, p99: 9600 ms), latency samples: 239420
5. check swarm health
Compatibility test for testnet_2d8b1b57553d869190f61df1aaf7f31a8fc19a7b ==> ee23d70eb9947415b6285c27cee498eb5b7ad7fe passed
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions]

✅ Forge suite land_blocking success on ee23d70eb9947415b6285c27cee498eb5b7ad7fe

performance benchmark : committed: 5479 txn/s, latency: 7242 ms, (p50: 5700 ms, p90: 11400 ms, p99: 26800 ms), latency samples: 2339550
Max round gap was 2 [limit 4] at version 636632. Max no progress secs was 4.89393 [limit 10] at version 636632.
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking

[github-actions]

✅ Forge suite framework_upgrade success on aptos-node-v1.3.0_3fc3d42b6cfe27460004f9a0326451bcda840a60 ==> ee23d70eb9947415b6285c27cee498eb5b7ad7fe

Compatibility test results for aptos-node-v1.3.0_3fc3d42b6cfe27460004f9a0326451bcda840a60 ==> ee23d70eb9947415b6285c27cee498eb5b7ad7fe (PR)
Upgrade the nodes to version: ee23d70eb9947415b6285c27cee498eb5b7ad7fe
framework_upgrade::framework-upgrade::full-framework-upgrade : committed: 4492 txn/s, latency: 7078 ms, (p50: 7500 ms, p90: 10200 ms, p99: 13900 ms), latency samples: 170720
5. check swarm health
Compatibility test for aptos-node-v1.3.0_3fc3d42b6cfe27460004f9a0326451bcda840a60 ==> ee23d70eb9947415b6285c27cee498eb5b7ad7fe passed
Test Ok

• Grafana dashboard
• Humio Logs
• Test runner output
• Test run is land-blocking