fix(inline-completion): potential inline completion failure due to input validation exception of supplemental context

[Will-ShaoHua]

Problem

ERROR: at 'supplementalContexts' failed to satisfy constraint: Member must have length less than or equal to 5

ERROR: supplementalContexts.1.member.content' failed to satisfy constraint: Member must have length less than or equal to 10240

Solution

Jebtrains PR aws/aws-toolkit-jetbrains#5466

 * Requirement
 * - Maximum 5 supplemental context.
 * - Each chunk can't exceed 10240 characters
 * - Sum of all chunks can't exceed 20480 characters

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[github-actions]

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