feat: implementing toxiproxy, testcontainers, and an integration test

[Mukamik]

Adding Testcontainers and Toxiproxy to demonstrate an integration test of database behaviour during network outage.

[NimJay]

Thanks for putting this together, @Mukamik!
Looks like the pos-pr-open-to-main GitHub check is failing.
I'm re-running to make sure it's not a flaky issue.

18:55:43.155 [main] DEBUG com.github.dockerjava.zerodep.shaded.org.apache.hc.client5.http.wire - http-outgoing-0 << "[read] I/O error: null"
18:55:43.156 [docker-java-stream--1841746279] DEBUG com.github.dockerjava.zerodep.shaded.org.apache.hc.client5.http.wire - http-outgoing-0 << "[read] I/O error: null"
18:55:43.161 [main] DEBUG com.github.dockerjava.zerodep.ApacheDockerHttpClientImpl$ApacheResponse - Failed to close the response
java.nio.channels.ClosedChannelException: null
	at java.base/sun.nio.ch.SocketChannelImpl.ensureOpenAndConnected(SocketChannelImpl.java:215)
	at java.base/sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:403)
	at java.base/sun.nio.ch.ChannelInputStream.read(ChannelInputStream.java:59)
	at java.base/sun.nio.ch.ChannelInputStream.read(ChannelInputStream.java:107)
	at java.base/sun.nio.ch.ChannelInputStream.read(ChannelInputStream.java:101)
	at com.github.dockerjava.zerodep.shaded.org.apache.hc.client5.http.impl.io.LoggingInputStream.read(LoggingInputStream.java:81)

[NimJay]

@Mukamik after re-running the pos-pr-open-to-main (point-of-sale-ci) GitHub check, we're getting the same error: 😅

20:36:27.088 [docker-java-stream-529698192] DEBUG com.github.dockerjava.zerodep.shaded.org.apache.hc.client5.http.wire - http-outgoing-0 << "[read] I/O error: null"
20:36:27.090 [main] DEBUG com.github.dockerjava.zerodep.ApacheDockerHttpClientImpl$ApacheResponse - Failed to close the response
java.nio.channels.ClosedChannelException: null
	at java.base/sun.nio.ch.SocketChannelImpl.ensureOpenAndConnected(SocketChannelImpl.java:215)
	at java.base/sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:403)
	at java.base/sun.nio.ch.ChannelInputStream.read(ChannelInputStream.java:59)

• Link to full Cloud Build logs here.
• Do you know if this could be related to the changes from this pull-request?

[Mukamik]

It looks like either a timeout during the integration test, which takes ~20 seconds to run outside of Cloud Build, or a slightly different exception than expected.

Either way it does look like the problem is in the branch. I'll address it then request review again.