[fix](typo) fix spelling typos in BE and cloud comments and messages

[spaces-X]

Proposed changes

Fix common spelling mistakes in code comments and a few user-facing log/error messages under be/src and cloud/src.

Examples: funciton → function, seperate → separate, unkown → unknown, invaild → invalid, avaliable → available, sucess → success, retrun → return, aquire → acquire, shoud → should, wether → whether, defalut → default, proccess → process.

It also renames one locally misspelled variable colunm → column in segment_iterator.cpp (3 occurrences in a single loop scope, no conflict).

Scope / safety

• 34 files, 46 lines, all under be/src and cloud/src.
• Comments and string literals only (plus the one local variable rename); no functional change.
• The whole-word replacement is underscore-aware, so it does not touch compound identifiers (e.g. test names like invaild_jsonb_document, test_signal_aquire) or intentional test data (e.g. unkown_resource_xxxxxx).
• Verified that none of the corrected message strings are asserted by any unit or regression test.

Types of changes

• Bugfix / typo (non-breaking change which fixes an issue)

[hello-stephen]

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