[SHIRO-793] deleteMe cookie should use the defined "sameSite"

[FredTreg]

With Chrome increasing security of cookies not defining any SameSite options, the deleteMe cookie may be blocked by Chrome under some circumstances.
For example, when an app is used within a cross-site iframe, one must defined the option SameSite=None option. This works for the main cookie, but the deleteMe is currently blocked. This commit fixes this.

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[bmarwell]

Thanks!

Can you please describe in a few words what the possible impacts are if not merging this commit?

[bdemers]

Merged to 1.6.x as well