Issue Description: When processing map tiles, an infinite loop of listing objects can be encountered.

• Dynmap Version: v3.0+ (since #3689)
• Server Version: all versions
• Other Relevant Data/Screenshots:
  here is a screenshot illustrating the phenomenon, with GET requests to minio in red, and other request methods in green:
  
  the switch from green to red coincides with the timing of the Full render of maps... completed message being displayed.

this bug occurs because of the use of getContinuationToken() rather than getNextContinuationToken() (AWS documentation)

• Steps to Replicate:

configure dynmap to use s3, and add a custom template suffix:

deftemplatesuffix: testing

and the normal-testing.txt to reproduce this:

version: 0.20
templates:
  normal-testing:
    enabled: true
    extrazoomout: 0
    maps:
      - class: org.dynmap.hdmap.HDMap
        name: e90
        title: "e90"
        prefix: e90
        perspective: iso_E_90_vlowres
        shader: stdtexture
        lighting: default
        mapzoomin: 0
      - class: org.dynmap.hdmap.HDMap
        name: s90
        title: "s90"
        prefix: s90
        perspective: iso_S_90_vlowres
        shader: stdtexture
        lighting: default
        mapzoomin: 0

after running /dynmap fullrender, the e90 render will complete, and then the s90 render will not begin.

[x] I have looked at all other issues and this is not a duplicate
[x] I have been able to replicate this