As a X-Road user I want that xroad-signer is profiled and possible bottlenecks are documented

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The xroad-signer process should be profiled and checked if there are any bottlenecks in the process that could be optimized. More information about the signer component is available here:

• https://docs.x-road.global/Architecture/arc-ss_x-road_security_server_architecture.html#26-signer
• https://docs.x-road.global/Architecture/arc-ss_x-road_security_server_architecture.html#32-xroad-signer

The JIRA ticket this issue was created from can be found here: https://nordic-institute.atlassian.net/browse/XRDDEV-1034

 Acceptance criteria:

• The xroad-signer process is profiled with JAVA 11 using the software token
• Benchmarking scripts and tools are documented
• Profiling results are analyzed and documented
• Suggestions for improving the code are documented