Fix get title logic to ignore the first extra large character in the abstract

[leaf-soba]

• Closes Parsing of "distributed systems online" paper does not work #12135.
• add an unit test case.
• fix the logic to ignore the first extra large character in the abstract.
• refactor it a little to make logic clear.

Mandatory checks

• I own the copyright of the code submitted and I licence it under the MIT license
• Change in CHANGELOG.md described in a way that is understandable for the average user (if change is visible to the user)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[koppor]

Thank you for the quick action taken.

The PDF itself is available without restrictions at https://www.computer.org/csdl/magazine/ds/2002/02/o2001/13rRUEgs2Q8 - thus, it is OK to version it.

Follow-up PR:

• Add .pdf to .bib
• Remove double spaces (we have this NormalizeWhiteSpaces)