* Add logging module to load log configuration dynamically
Signed-off-by: NGao Hongtao <hanahmily@gmail.com>

* bump up envoy metrics service sinks version. and update envoy.yaml config for demo.

* Upgrade agent plugin for ElasticJob 3.0.0 GA version.

* Remove 3.0.0 alpha support.

Remove the following plugins due to they are legacy and unstable releases.
1. sharding-jdbc-1.5.x-plugin
2. sharding-sphere-4.x-rc3-plugin
3. sharding-sphere-4.x-plugin (This is for RC1 and RC2)

To people who want to use these removing versions, you still could copy the plugins from SkyWalking's 8.6.0 release to the '/plugins' folder to activate, unless SkyWalking has some core level APIs upgrade. This is very rare to happen.

Logically revert #6642 and partial #7153 to reduce unnecessary thread and concurrency process (#7318)

 The key logic behinds all these is, metrics persistence is fully asynchronous.

* The core/maxSyncOperationNum setting(added in 8.5.0) is removed due to metrics persistence is fully asynchronous.
* The core/syncThreads setting(added in 8.5.0) is removed due to metrics persistence is fully asynchronous.
* Optimization: Concurrency mode of execution stage for metrics is removed(added in 8.5.0). The only concurrency of prepare stage is meaningful and kept.
* Remove the outside preparedRequest list initialization, worker instance could always build a suitable size list in the first place (Reduce Array.copy and GC load a little).

Adjust index refresh period as INT(flushInterval * 2/3), it used to be as same as bulk flush period. At the edge case, in low traffic(traffic < bulkActions in the whole period), there is a possible case, 2 period bulks are included in one index refresh rebuild operation, which could cause version conflicts. And this case can't be fixed through core/persistentPeriod as the bulk fresh is not controlled by the persistent timer anymore.

This PR should avoid the following exception in the low load case, especially when bulkActions is set larger than the number of a metric type.

* Performance: remove the synchronous persistence mechanism from batch ElasticSearch DAO. Because the current enhanced persistent session mechanism, don't require the data queryable immediately after the insert and update anymore.
* Performance: share `flushInterval` setting for both metrics and record data, due to `synchronous persistence mechanism` removed. Record flush interval used to be hardcoded as 10s.
* Remove `syncBulkActions` in ElasticSearch storage option.
* Increase the default bulkActions(env, SW_STORAGE_ES_BULK_ACTIONS) to 5000(from 1000).
* Increase the flush interval of ElasticSearch indices to 15s(from 10s)

Add these 2 references. According to these, **(same _index, _type and _id) in same bulk will be in order**
1. https://github.com/elastic/elasticsearch/issues/50199
2. https://discuss.elastic.co/t/order-of--bulk-request-operations/98124

Notice, the order of different bulks is not guaranteed by the ElasticSearch cluster. We are going to have the risk of dirty write. But consider we set over 20s period between flush, and index flush period is 10, we should be safe.

Recommend 5000 bulk size and 15s flush interval only. The persistent period has been set to 25s.

* Allow configuring max request header size

This allows configuring the HTTP max request header size from the jetty
server.
By default it uses 8192, the same jetty default.

1.0Performance: Add L1 aggregation flush period, which reduces the CPU load and helps young GC.

2. Replace do not direct send after the first aggregation to reduce the network #6400.

3. Enhance the DataCarrier to notify the consumer in no enqueue event in short term.

4. L1 aggregation flush period still works even no further metrics generated, powered by <3>

5. Fix gRPC remote client OOM. The concurrency control mechanism failed.

* OAL supports generating metrics from events

* Add new dashboard for event metrics

* Add some docs for event metrics