Update delete and insert tests in test-suite/,

[panarch]

Add delete test which is for testing DELETE statements.
Update insert test - format codes and add an error case.

[coveralls]

Pull Request Test Coverage Report for Build 4913439548

• 68 of 68 (100.0%) changed or added relevant lines in 3 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.04%) to 98.983%

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Files with Coverage Reduction	New Missed Lines	%
core/src/data/interval/mod.rs	1	99.75%

Totals
Change from base Build 4901599711:	0.04%
Covered Lines:	42829
Relevant Lines:	43269

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💛 - Coveralls