Remove redundant if-else in EXPLAIN by using ExplainPropertyText

Hi hackers,

Thanks to David [0], we found that the if and else branches contained 
equivalent code. Since ExplainPropertyText already handles non-text 
formats, the extra condition is unnecessary.

I reviewed other files related to EXPLAIN where similar patterns might 
exist, but this was the only instance I found.

I’m attaching a patch with the fix. If anyone spots a similar case 
elsewhere, please let me know.

[0]: 
https://www.postgresql.org/message-id/CAApHDvpq2gOt3gnzkd4Ud%3DwrT7YRGrF3zb29jgWzDsYEhETrOA%40mail.gmail.com

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Best regards,
Ilia Evdokimov,
Tantor Labs LLC.