Make javadoc <p> style guide compliant

This led to confusion for an open source contributor about how to format
code. We don't want to be like, "do as I say, not as I do."

https://google.github.io/styleguide/javaguide.html#s7.1.2-javadoc-paragraphs
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=122589700

java/google/registry/tools/params/DateTimeParameter.java

@@ -35,8 +35,8 @@ public final class DateTimeParameter extends ParameterConverterValidator<DateTim
    * Parser for DateTimes that permits only a restricted subset of ISO 8601 datetime syntax.
    * The supported format is "YYYY-MM-DD'T'HH:MM:SS[.SSS]ZZ", i.e. there must be a complete date
    * and at least hours, minutes, seconds, and time zone; milliseconds are optional.
-   * <p>
-   * We use this instead of the default {@link ISODateTimeFormat#dateTimeParser()} because that
+   *
+   * <p>We use this instead of the default {@link ISODateTimeFormat#dateTimeParser()} because that
    * parser is very flexible and accepts date times with missing dates, missing dates, and various
    * other unspecified fields that can lead to confusion and ambiguity.
    */