fix: prevent ReDoS vulnerabilities and improve cookie security

[marevol]

Summary

This PR addresses security vulnerabilities related to regular expression denial of service (ReDoS) and improves cookie handling consistency for search parameters.

Changes Made

ReDoS Prevention in Dictionary Files

• CharMappingFile.java: Changed regex pattern from (.*)\\s*=>\\s*(.*)\\s*$ to (.*?)\\s*+=>\\s*+(.*?)\\s*+$
• StemmerOverrideFile.java: Applied the same regex pattern fix

The original greedy quantifiers (*) combined with backtracking could cause exponential time complexity on certain malformed inputs. Using non-greedy quantifiers (*?) with possessive quantifiers (*+) prevents catastrophic backtracking.

Cookie Security Improvements in SearchHelper

• Extracted isSearchParameterCookieSecure() method to centralize the logic for determining cookie secure flag
• Added missing httpOnly and secure flags when invalidating the search parameter cookie
• Previously, when clearing the cookie (setting maxAge to 0), the cookie attributes were inconsistent with the original cookie, which could lead to the cookie not being properly invalidated in some browsers

S3 Endpoint Detection Fix in StorageClientFactory

• Replaced regex pattern .*s3[.-].* with simpler string contains checks: contains("s3.") or contains("s3-")
• The previous regex pattern was susceptible to ReDoS and unnecessary for simple substring matching

Testing

• Verified regex patterns compile correctly
• The changes are backward-compatible and do not alter the functional behavior

Breaking Changes

None. These are internal implementation improvements that maintain the same external behavior.

Additional Notes

These fixes address potential security vulnerabilities that could be exploited through carefully crafted input to cause CPU exhaustion via regex backtracking.