API calls that omit `limit` should not fail

[abitmore]

Bug Description

For APIs with an optional limit, If the node operator configured a smaller limit, the API call should not fail if the client does not specify a limit.

Impacts Describe which portion(s) of BitShares Core may be impacted by this bug. Please tick at least one box.

• [x] API (the application programming interface)
• [ ] Build (the build process or something prior to compiled code)
• [ ] CLI (the command line wallet)
• [ ] Deployment (the deployment process after building such as Docker, Travis, etc.)
• [ ] DEX (the Decentralized EXchange, market engine, etc.)
• [ ] P2P (the peer-to-peer network for transaction/block propagation)
• [ ] Performance (system or user efficiency, etc.)
• [ ] Protocol (the blockchain logic, consensus, validation, etc.)
• [ ] Security (the security of system or user data, etc.)
• [x] UX (the User Experience)
• [ ] Other (please add below)

Host Environment Please provide details about the host environment. Much of this information can be found running: witness_node --version.

• Host OS: [e.g. Ubuntu 18.04 LTS]
• Host Physical RAM [e.g. 4GB]
• BitShares Version: [e.g. 2.0.180425]
• OpenSSL Version: [e.g. 1.1.0g]
• Boost Version: [e.g. 1.65.1]

CORE TEAM TASK LIST

• [ ] Evaluate / Prioritize Bug Report
• [ ] Refine User Stories / Requirements
• [ ] Define Test Cases
• [ ] Design / Develop Solution
• [ ] Perform QA/Testing
• [ ] Update Documentation

[abitmore]

Fixed by #2622.