Reproduction case of exception thrown when disabling check thats also in XepPatchChecks

[oxkitsune]

When disabling a check using -Xep:XXX:OFF while the check is listed in -XepPatchChecks results in a NoSuchElementException being thrown when EP tries to get the severity level of the check.

This PR introduces code that triggers the StaticImport check to get a reproducible case.

The issue can be reproduced using the following mvn invocation:

mvn clean install \
-Perror-prone \
-Derror-prone.patch-args="-XepPatchLocation:IN_PLACE -XepPatchChecks:StaticImport -Xep:StaticImport:OFF"

And results in the following exception:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.10.1:compile (default-compile) on project error-prone-demo: Compilation failure
[ERROR] ~/error-prone-demo/src/main/java/com/example/HelloWorld.java:[22,64] An unhandled exception was thrown by the Error Prone static analysis plugin.
[ERROR]      Please report this at https://github.com/google/error-prone/issues/new and include the following:
[ERROR]
[ERROR]      error-prone version: 2.19.1
[ERROR]      BugPattern: StaticImport
[ERROR]      Stack Trace:
[ERROR]      java.util.NoSuchElementException: No value present
[ERROR]   	at java.base/java.util.Optional.get(Optional.java:143)
[ERROR]   	at com.google.errorprone.matchers.Description.severity(Description.java:78)
[ERROR]   	at com.google.errorprone.ErrorProneAnalyzer.lambda$finished$1(ErrorProneAnalyzer.java:138)
[ERROR]   	at com.google.errorprone.VisitorState.reportMatch(VisitorState.java:301)
[ERROR]   	at com.google.errorprone.scanner.Scanner.reportMatch(Scanner.java:127)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.processMatchers(ErrorProneScanner.java:448)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitMemberSelect(ErrorProneScanner.java:726)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitMemberSelect(ErrorProneScanner.java:150)

[rickie]

As discussed offline; related Error Prone issue: google/error-prone#3908.